Episode 5

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0:00:02 > 0:00:06We're discovering astonishing things about the human body all the time

0:00:06 > 0:00:08through people who are different from most.

0:00:10 > 0:00:12I'm Gabriel Weston.

0:00:12 > 0:00:15As a surgeon, I've spent years studying the human body.

0:00:17 > 0:00:22And the secrets of how it works are often revealed by the most rare and

0:00:22 > 0:00:23surprising of cases.

0:00:25 > 0:00:29So I've searched the world to find these extraordinary people

0:00:29 > 0:00:31and bring you their stories.

0:00:32 > 0:00:37This is my heart. I'm the only one that has this.

0:00:37 > 0:00:39I'm Jodi Seneca, and I can't feel fear.

0:00:39 > 0:00:43My name is Harnaam Kaur, and I'm a fabulous bearded lady.

0:00:43 > 0:00:46With the help of the doctors that treat them

0:00:46 > 0:00:49and some of the world's leading scientists,

0:00:49 > 0:00:54I'll be uncovering exactly what makes their bodies unique.

0:00:55 > 0:01:00I'm going to show you the hidden processes that make them exceptional.

0:01:02 > 0:01:03Just look at that!

0:01:05 > 0:01:10I'll discover how they're leading us to the cures of the future.

0:01:10 > 0:01:13When we make a breakthrough like this, it is very exciting.

0:01:14 > 0:01:20And I'll use the latest technology to uncover the secrets of their bodies

0:01:20 > 0:01:25and reveal how all of these cases are giving us a new understanding

0:01:25 > 0:01:30of the most amazing natural machine on the planet.

0:01:30 > 0:01:32The human body.

0:01:46 > 0:01:51There's no time in life more amazing than the nine months we spend

0:01:51 > 0:01:53developing inside the womb.

0:01:53 > 0:01:57We go from two single cells, a sperm and an egg,

0:01:57 > 0:02:00to a fully fledged human being within the space of a year.

0:02:02 > 0:02:06It's one of the most incredible transformations in the natural world.

0:02:08 > 0:02:13And the slightest mistake can shape our bodies in extraordinary ways.

0:02:14 > 0:02:20In this programme we'll discover why this man has super-strong bones,

0:02:20 > 0:02:23why this woman has two wombs,

0:02:23 > 0:02:28why this girl's arm won't stop growing

0:02:28 > 0:02:32and why this boy's cells were re-engineered to save his life.

0:02:35 > 0:02:39The tiniest flaw or mutation that occurs when a cell divides,

0:02:39 > 0:02:41even in a single gene,

0:02:41 > 0:02:45can have the most enormous impact on how our bodies work.

0:02:45 > 0:02:50And this is bringing some of the most exciting new discoveries in medicine,

0:02:50 > 0:02:52as our first case shows.

0:02:55 > 0:02:58Ceniya looks like a pretty normal ten-year-old.

0:02:58 > 0:03:01I like to do basketball, tennis, archery,

0:03:01 > 0:03:04swimming and dancing and gymnastics.

0:03:06 > 0:03:09And this makes her extraordinary.

0:03:09 > 0:03:10My name is Ceniya.

0:03:10 > 0:03:12I have a sickle cell disease, but I am not sick.

0:03:14 > 0:03:18Ceniya has a debilitating disease called sickle cell.

0:03:18 > 0:03:20She shouldn't be able to run around like this.

0:03:20 > 0:03:23But it looks as though nobody has told Ceniya.

0:03:26 > 0:03:29When Ceniya was born, she was a sweetheart.

0:03:29 > 0:03:31You know, she was always smiling, always playful.

0:03:33 > 0:03:35But shortly after she was born,

0:03:35 > 0:03:37Ceniya was diagnosed with sickle cell...

0:03:39 > 0:03:43..a blood disease that can lead to pain, strokes and infections.

0:03:43 > 0:03:45It can be fatal.

0:03:45 > 0:03:47And, as yet, there is no cure.

0:03:51 > 0:03:55We were told it was the worst type and, basically,

0:03:55 > 0:03:58that she's going to have all these crises,

0:03:58 > 0:04:01and going through pain all her life,

0:04:01 > 0:04:03and her life expectancy was going to be low.

0:04:03 > 0:04:05That moment was just devastating.

0:04:08 > 0:04:13Sickle cell disease is an inherited condition that requires inheriting a

0:04:13 > 0:04:16faulty gene from your mother and your father.

0:04:16 > 0:04:19It's suffered mainly by the African-Caribbean community.

0:04:20 > 0:04:23I have family members that have sickle cell disease,

0:04:23 > 0:04:28and I've seen the pain, and all of the agony that they go through,

0:04:28 > 0:04:29and all the hospital stays.

0:04:29 > 0:04:31So I cried a lot.

0:04:31 > 0:04:34You know, just knowing my daughter was going to have to go through this.

0:04:36 > 0:04:41Ceniya was referred to the Children's Cancer and Blood Disorder Center in Boston.

0:04:41 > 0:04:46Her doctor is Matthew Heaney, who specialises in sickle cell disease.

0:04:47 > 0:04:50Sickle cell disease is a disease of the red blood cell.

0:04:50 > 0:04:53In our body we have trillions of red blood cells.

0:04:53 > 0:04:55Red blood cells move through the blood vessels

0:04:55 > 0:04:58to mostly deliver oxygen to the rest of our body.

0:04:58 > 0:05:00All of our tissues and organs need oxygen.

0:05:02 > 0:05:05Red blood cells are full of haemoglobin,

0:05:05 > 0:05:08a protein that carries the oxygen, seen here in blue.

0:05:11 > 0:05:15Normally, these cells are disc-shaped and flexible.

0:05:15 > 0:05:18But sickle cell patients have a faulty version of haemoglobin.

0:05:20 > 0:05:25After it's delivered its oxygen to the body it causes a catastrophic change

0:05:25 > 0:05:26in the shape of the red blood cells.

0:05:28 > 0:05:32The diseased cells form an abnormal sickle shape,

0:05:32 > 0:05:36and these little sickles, within the red blood, are rigid,

0:05:36 > 0:05:39and they get stuck in the blood vessels,

0:05:39 > 0:05:42causing pain and other things like strokes.

0:05:44 > 0:05:47But Ceniya is not suffering any of these symptoms.

0:05:49 > 0:05:50How you been since I last saw you?

0:05:50 > 0:05:53- Good.- You had any problems?

0:05:53 > 0:05:56And it doesn't look like you've been in that emergency room since I last saw you.

0:05:56 > 0:05:57No.

0:05:58 > 0:06:02Since being diagnosed with sickle cell disease as a baby,

0:06:02 > 0:06:07Ceniya's family have been expecting her to fall seriously ill at any moment.

0:06:07 > 0:06:10But it hasn't happened.

0:06:10 > 0:06:13How can Ceniya have a life-threatening illness

0:06:13 > 0:06:15but no symptoms?

0:06:17 > 0:06:19Dr Heaney was determined to find out.

0:06:19 > 0:06:24So when Ceniya was one year old, he took a blood sample.

0:06:24 > 0:06:28And he found out that it contained high levels of a type of haemoglobin

0:06:28 > 0:06:30he wasn't expecting to see...

0:06:31 > 0:06:33..foetal haemoglobin,

0:06:33 > 0:06:37a kind we have when we're still in our mother's womb

0:06:37 > 0:06:40and not yet taking in oxygen by breathing.

0:06:43 > 0:06:46It's a very special type of haemoglobin, for that environment.

0:06:46 > 0:06:48It has a very high affinity for oxygen,

0:06:48 > 0:06:50meaning it holds on to oxygen tightly,

0:06:50 > 0:06:54and can extract oxygen from the mother's placenta for life in the womb.

0:06:56 > 0:07:00The instant we're born, we're suddenly in an environment

0:07:00 > 0:07:02with much more oxygen.

0:07:02 > 0:07:07It means our blood needs to adapt quickly in the very earliest moments

0:07:07 > 0:07:09of life.

0:07:09 > 0:07:12And I'm going to show you one of the many reasons why.

0:07:14 > 0:07:16Now, obviously, we need oxygen to survive.

0:07:16 > 0:07:18But if we have too much of it,

0:07:18 > 0:07:23it can cause the formation of highly reactive and damaging molecules.

0:07:23 > 0:07:27Now, this is one such highly reactive substance.

0:07:27 > 0:07:29It's known as hydrogen peroxide,

0:07:29 > 0:07:33and it can cause a huge amount of damage within the body.

0:07:33 > 0:07:36Now, if I add some of this substance to water...

0:07:38 > 0:07:40..very little happens.

0:07:40 > 0:07:43But look what happens when I add it to blood.

0:07:44 > 0:07:46Just look at that!

0:07:47 > 0:07:51Now, obviously, newborn blood doesn't foam and bubble in that way,

0:07:51 > 0:07:54but the principle is the same.

0:07:54 > 0:07:56There's an enzyme in the blood called catalase,

0:07:56 > 0:08:01and what that's doing right now is neutralising the hydrogen peroxide

0:08:01 > 0:08:04in a way that makes it less harmful.

0:08:04 > 0:08:08Newborn babies have extra levels of this catalase in their blood,

0:08:08 > 0:08:10in the first few days of life,

0:08:10 > 0:08:15while they're becoming accustomed to the extra oxygen in the outside world.

0:08:17 > 0:08:21As soon as a baby is born, one of the key changes in their blood

0:08:21 > 0:08:25is that they switch from foetal to adult haemoglobin,

0:08:25 > 0:08:28which adapts to the extra oxygen in the air.

0:08:31 > 0:08:33By the time we're a year old,

0:08:33 > 0:08:37most of us only have a trace of foetal haemoglobin left.

0:08:37 > 0:08:38About 1%.

0:08:40 > 0:08:42But Ceniya is different.

0:08:42 > 0:08:45At the age of one, she had more than 30%.

0:08:47 > 0:08:51And Dr Heaney suspected that this was why she wasn't displaying

0:08:51 > 0:08:53any of the symptoms of her disease,

0:08:53 > 0:08:58because foetal haemoglobin doesn't form the problematic sickle shape.

0:09:00 > 0:09:04Sickle haemoglobin sticks together when it's lost its oxygen.

0:09:04 > 0:09:06The foetal haemoglobin doesn't participate in that sticking together.

0:09:06 > 0:09:08So the more foetal haemoglobin you have,

0:09:08 > 0:09:10it interferes with that interaction,

0:09:10 > 0:09:13and allows the cell to stay in a nice disc shape,

0:09:13 > 0:09:16and not take up the stiff and unbendable sickle form.

0:09:18 > 0:09:21Ceniya's case is highly unusual.

0:09:21 > 0:09:26So why is it that most of us switch almost entirely from foetal

0:09:26 > 0:09:32to adult haemoglobin at birth but rare individuals like Ceniya don't?

0:09:35 > 0:09:38Scientists hope that if they could uncover that secret,

0:09:38 > 0:09:42it might lead to a new treatment for sickle cell disease.

0:09:43 > 0:09:48Dr Stuart Orkin is a researcher at the Boston Children's Cancer and

0:09:48 > 0:09:49Blood Disorders Center.

0:09:52 > 0:09:56One of the really central research activities within the entire field

0:09:56 > 0:10:00has been to try to understand how it is that we switch

0:10:00 > 0:10:03from a foetal haemoglobin to an adult haemoglobin,

0:10:03 > 0:10:06which occurs, really, around the time of birth.

0:10:09 > 0:10:14Dr Orkin suspected we must have specific genes responsible for the

0:10:14 > 0:10:18crucial switch from foetal to adult haemoglobin.

0:10:18 > 0:10:22For 30 years, he combed through the genes of families with

0:10:22 > 0:10:24and without the disease,

0:10:24 > 0:10:28searching for one tiny difference that could lead him to the switch.

0:10:29 > 0:10:33Eventually, he found a gene called BCL 11A

0:10:33 > 0:10:37that seems to be different in people with sickle cell disease.

0:10:38 > 0:10:40It was a major step forward,

0:10:40 > 0:10:46but now Dr Orkin desperately needed to find out if this gene really

0:10:46 > 0:10:48could be the switch he'd been looking for.

0:10:51 > 0:10:55To find out, Dr Orkin did some experiments with mice.

0:10:56 > 0:10:59He took a mouse with sickle cell disease

0:10:59 > 0:11:02and removed the BCL 11A gene.

0:11:03 > 0:11:06What he discovered was remarkable.

0:11:07 > 0:11:12This is the image of a blood smear of a mouse with sickle cell disease.

0:11:13 > 0:11:17You can see these funny-shaped cells, sickle cells.

0:11:17 > 0:11:22Now, we've taken this kind of mouse, and we've removed the gene.

0:11:22 > 0:11:24And when we do that,

0:11:24 > 0:11:29you can see that the cells now take on the normal appearance.

0:11:29 > 0:11:31They are now quite round and uniform.

0:11:31 > 0:11:35These mice have normal blood and a normal life span.

0:11:35 > 0:11:41So that experiment demonstrates that removing the gene cures sickle cell

0:11:41 > 0:11:43disease, at least in this mouse model.

0:11:45 > 0:11:48This is an exciting breakthrough.

0:11:48 > 0:11:52By removing one gene, scientists have altered the switch.

0:11:52 > 0:11:56So the mouse continues to produce more foetal haemoglobin,

0:11:56 > 0:11:59which doesn't form sickle cells.

0:11:59 > 0:12:03Now there's a new hope of a treatment for sickle cell patients.

0:12:05 > 0:12:10The goal would be to be able to have a pill that we could give to an

0:12:10 > 0:12:14individual and instead of having 1% foetal haemoglobin,

0:12:14 > 0:12:17maybe we'd have 10%.

0:12:17 > 0:12:23And I don't dare predict when, and if, that will occur.

0:12:23 > 0:12:26But it's a goal that is worthy of research.

0:12:32 > 0:12:35If Dr Orkin can harness what he's learned in his research,

0:12:35 > 0:12:40tens of thousands of people suffering from sickle cell disease might have,

0:12:40 > 0:12:44in their future, the possibility of leading healthy, active lives.

0:12:44 > 0:12:46Just like Ceniya.

0:12:48 > 0:12:53I hope that soon, like, when I get older, the doctors find my cure,

0:12:53 > 0:12:56and they give it to those people, and they, finally, can do what I do.

0:12:58 > 0:13:00Ceniya for president, remember I said that.

0:13:00 > 0:13:01THEY LAUGH

0:13:05 > 0:13:08Ceniya's case shows us one single,

0:13:08 > 0:13:14but vital, stage in the unimaginably complex process of how we grow and

0:13:14 > 0:13:19develop from one tiny bundle of cells in our mother's womb

0:13:19 > 0:13:22to a fully formed human made up of trillions of cells.

0:13:24 > 0:13:26The next cases we'll look at reveal

0:13:26 > 0:13:30how these cells that our bodies are made up of

0:13:30 > 0:13:32can grow in extraordinary ways.

0:13:36 > 0:13:40In 2005, Clare Miles gave birth to twins.

0:13:42 > 0:13:45But this had been no ordinary pregnancy...

0:13:47 > 0:13:50..because Claire has two wombs.

0:13:52 > 0:13:55And each baby grew in a separate womb.

0:13:56 > 0:14:01Claire was born with a condition called uterus didelphys.

0:14:01 > 0:14:05She was completely unaware of it until she was 20,

0:14:05 > 0:14:07when she had to have emergency surgery.

0:14:08 > 0:14:12I'd had an abscess on my vagina wall, which

0:14:12 > 0:14:16had caused a great deal of pain.

0:14:16 > 0:14:21And I woke up to discover that I had...

0:14:21 > 0:14:22two wombs.

0:14:24 > 0:14:27Claire's condition helps us understand

0:14:27 > 0:14:30how our bodies are formed in the womb.

0:14:33 > 0:14:37Normally, the female foetus starts off with two separate tubes that

0:14:37 > 0:14:42eventually fuse to form a single womb.

0:14:42 > 0:14:46But in about 3% of babies, this fusing process gets disrupted.

0:14:48 > 0:14:52And in some rare cases, a girl is born with two wombs, like Claire.

0:14:55 > 0:14:58It's even more rare, and very risky,

0:14:58 > 0:15:00to have a pregnancy in both wombs at once.

0:15:02 > 0:15:06That's because each uterus can go into labour at a different time.

0:15:09 > 0:15:11But on the 8th of June 2005,

0:15:11 > 0:15:14Maisie Rose and Noah Henry both arrived safely

0:15:14 > 0:15:16by Caesarean section.

0:15:24 > 0:15:26It's often in cases like these,

0:15:26 > 0:15:29where a person's body grows in an unusual way,

0:15:29 > 0:15:33that we can trace back to the beginning of the process,

0:15:33 > 0:15:36and uncover the secrets of how our body's built.

0:15:38 > 0:15:39In our next case,

0:15:39 > 0:15:44we'll meet one girl whose body isn't growing the way most of us do.

0:15:48 > 0:15:52Hi, I'm Leah Hardcastle, I'm 14, and I love to ride horses.

0:15:53 > 0:15:58Leah has a very unusual condition that affects how her body grows.

0:15:59 > 0:16:01She's had this from birth, and really,

0:16:01 > 0:16:05it's just where certain areas of Leah's body are growing far quicker

0:16:05 > 0:16:07than other parts of her body.

0:16:09 > 0:16:12My arm just looked different.

0:16:12 > 0:16:15I mean, this arm is absolutely fine.

0:16:15 > 0:16:18No problems. And then the left arm, my hand,

0:16:18 > 0:16:20it just looked out of proportion.

0:16:24 > 0:16:27It turns out Leah is one of very few people

0:16:27 > 0:16:31who are suffering from a condition called segmental overgrowth.

0:16:31 > 0:16:32And what that means

0:16:32 > 0:16:39is that Leah's left arm is growing continually at an abnormal rate.

0:16:41 > 0:16:46In 14 years, she's had over 30 operations to reduce the size of her arm.

0:16:48 > 0:16:51Each surgery, it will get better for a few months,

0:16:51 > 0:16:56and then it might just grow really fast,

0:16:56 > 0:16:58or it will grow eventually.

0:17:00 > 0:17:05This is a condition that doesn't affect any other part of Leah's body.

0:17:05 > 0:17:08Only her left arm keeps growing.

0:17:08 > 0:17:09So why does this happen?

0:17:10 > 0:17:14The answer could lie in pioneering research being carried out by

0:17:14 > 0:17:16scientists in Cambridge.

0:17:17 > 0:17:18My name is Robert Semple,

0:17:18 > 0:17:21I'm a principal investigator at the University of Cambridge

0:17:21 > 0:17:23in metabolic science.

0:17:23 > 0:17:27Dr Semple believes Leah's condition has its origins in the very

0:17:27 > 0:17:29earliest days of life in the womb,

0:17:29 > 0:17:32when an embryo is made up of just a few cells.

0:17:35 > 0:17:38We all start out as a fertilised egg,

0:17:38 > 0:17:42and in that egg there is a shuffling of the genes from our mother and

0:17:42 > 0:17:45father. And it provides the full complement of genes

0:17:45 > 0:17:49which are transmitted to all the cells of our body in adult life.

0:17:49 > 0:17:51So one cell becomes two cells,

0:17:51 > 0:17:54that becomes four cells,

0:17:54 > 0:17:58but this all relies on all 20,000 genes being copied accurately.

0:17:58 > 0:18:03And if there's a change in a gene which allows a cell to survive,

0:18:03 > 0:18:05and which changes the properties of that cell,

0:18:05 > 0:18:07then this will appear at this stage,

0:18:07 > 0:18:10so this is represented here by yellow.

0:18:10 > 0:18:13So we now have a situation where the embryo contains a mixture of normal

0:18:13 > 0:18:17cells, with the same genes as the parents, and one abnormal cell.

0:18:20 > 0:18:25In Leah's case, the part of her body that has become her left arm had a

0:18:25 > 0:18:29mutation in one of the genes that meant that that part of her body has

0:18:29 > 0:18:31developed abnormally.

0:18:32 > 0:18:36And Dr Semple had a good idea which gene was responsible.

0:18:37 > 0:18:42By the time we met Leah we had worked out from studying similar patients

0:18:42 > 0:18:45that nearly always the change was in the PIK3CA gene, so therefore,

0:18:45 > 0:18:48we focused first on the PIK3CA gene.

0:18:50 > 0:18:54PIK3CA is a gene that is involved in controlling growth.

0:18:56 > 0:19:01Because Leah has an abnormality at this particular point in her genetics,

0:19:01 > 0:19:05what that means is that her cells just don't know when to stop growing.

0:19:07 > 0:19:10This reminded Dr Semple of a different illness altogether...

0:19:12 > 0:19:14..cancer,

0:19:14 > 0:19:19a disease that's also caused by an uncontrolled growth of abnormal cells

0:19:19 > 0:19:21in a part of the body.

0:19:21 > 0:19:24And this similarity gave him an idea.

0:19:25 > 0:19:28We knew that if we could take some of those medicines which were being

0:19:28 > 0:19:32used in cancer, it might give us a chance of reducing the growth,

0:19:32 > 0:19:35possibly even shrinking down the extra growth in patients like Leah.

0:19:38 > 0:19:41Leah has just been involved in an initial trial

0:19:41 > 0:19:44of one particular cancer drug,

0:19:44 > 0:19:46and has come to Addenbrooke's Hospital in Cambridge.

0:19:48 > 0:19:50The machines will come to the top of your head.

0:19:50 > 0:19:53And when it's scanning back down is when it's actually scanning you.

0:19:53 > 0:19:54OK?

0:19:54 > 0:19:58Scientists are scanning Leah's body so they can monitor the mass

0:19:58 > 0:19:59of her arm.

0:20:02 > 0:20:05The top arm seems to have stayed

0:20:05 > 0:20:07roughly the same.

0:20:09 > 0:20:11This time there's not much change.

0:20:11 > 0:20:13But it's early days for the research,

0:20:13 > 0:20:17and this is just one drug among several that Dr Semple intends to

0:20:17 > 0:20:21trial in the hope that a cure can be found for patients like Leah

0:20:21 > 0:20:23in the future.

0:20:26 > 0:20:30She has played a really important part,

0:20:30 > 0:20:33and we will be running more studies starting next year,

0:20:33 > 0:20:34and in subsequent years,

0:20:34 > 0:20:38and we'll make sure we offer her the chance to play her part in those as well.

0:20:39 > 0:20:44If these trials really do help, I'd be up for it.

0:20:44 > 0:20:48Any time. Because helping anyone else is just my main priority.

0:20:54 > 0:20:59Leah's story reveals the key process in our transformation from a bundle

0:20:59 > 0:21:02of cells to a fully fledged adult.

0:21:02 > 0:21:07As we grow and develop, our cells divide and divide again.

0:21:07 > 0:21:10But this process is anything but haphazard.

0:21:10 > 0:21:14It needs to happen in a controlled way,

0:21:14 > 0:21:19and among the most astonishing cases in the history of medicine is one

0:21:19 > 0:21:21where the cells just didn't know when to stop.

0:21:25 > 0:21:29Henrietta Lacks has the most extraordinary cells on the planet.

0:21:30 > 0:21:34Yet she died more than 60 years ago.

0:21:34 > 0:21:38And in her lifetime, there seemed nothing remarkable about her.

0:21:39 > 0:21:43Henrietta Lacks came to Baltimore with her husband,

0:21:43 > 0:21:49they lived in an area where many African-Americans from the South came.

0:21:51 > 0:21:55James Potter is assistant professor of medicine at the Johns Hopkins

0:21:55 > 0:21:57University in Baltimore.

0:21:59 > 0:22:03She went to a doctor complaining of pain,

0:22:03 > 0:22:06and he referred her to Johns Hopkins.

0:22:06 > 0:22:10That's when her cervical cancer was discovered.

0:22:12 > 0:22:16The doctors found a tumour and took biopsies for testing.

0:22:16 > 0:22:20But her cancer had spread, and Henrietta died.

0:22:20 > 0:22:22She was just 31 years old.

0:22:24 > 0:22:28But the cells from her biopsies were still in the hospital laboratory,

0:22:28 > 0:22:34and the lab technicians noticed they were doing something very unusual.

0:22:34 > 0:22:38The technicians were the first to really get excited,

0:22:38 > 0:22:44when they saw that there were individual cells growing.

0:22:44 > 0:22:48They knew this was different from all other attempts

0:22:48 > 0:22:51to grow human cells in culture.

0:22:53 > 0:22:58Back in the 1950s, scientists were only able to preserve human cells

0:22:58 > 0:23:02outside the body for a few days or weeks.

0:23:02 > 0:23:06They wanted to use them for vital research into cancer and other diseases.

0:23:07 > 0:23:11But often the cells would die before their investigations were complete.

0:23:13 > 0:23:15Henrietta's cells were different.

0:23:19 > 0:23:22These cells continued to grow.

0:23:22 > 0:23:26The researchers were able to grow them in large quantities,

0:23:26 > 0:23:31they did not begin to die off or to change their characteristics.

0:23:33 > 0:23:38This is a time-lapse of cells taken from Henrietta Lacks's tumour.

0:23:38 > 0:23:41They were multiplying at an astonishing rate,

0:23:41 > 0:23:44each cell dividing every 20 hours.

0:23:46 > 0:23:49And here they are six weeks later, they are still alive,

0:23:49 > 0:23:51and thriving in the test tube.

0:23:53 > 0:23:59Even if they are in the air or on a benchtop, they still survive,

0:23:59 > 0:24:03they were entirely different from any cells isolated previously.

0:24:06 > 0:24:11Here were human cells that appeared to be immortal.

0:24:11 > 0:24:14Scientists could experiment on them safe in the knowledge

0:24:14 > 0:24:17that these cells wouldn't die.

0:24:17 > 0:24:18So how is this possible?

0:24:20 > 0:24:26Inside our cells our DNA is arranged in structures called chromosomes.

0:24:26 > 0:24:31The tips of our chromosomes are called telomeres.

0:24:31 > 0:24:34Each time a cell divides, these become shorter.

0:24:35 > 0:24:39When they get too short, our cells stop dividing and die.

0:24:41 > 0:24:43But in Henrietta Lacks's cells,

0:24:43 > 0:24:48researchers found high levels of an enzyme called telomerase.

0:24:48 > 0:24:52This rebuilds the telomeres so they don't shorten.

0:24:52 > 0:24:54And that's why her cells weren't dying.

0:24:56 > 0:24:59Using letters from Henrietta Lacks's name,

0:24:59 > 0:25:02scientists called these cells HeLa.

0:25:02 > 0:25:06And soon they began to be shipped to laboratories around the world

0:25:06 > 0:25:09for research into new treatments and cures.

0:25:12 > 0:25:16Having the immortal cell line, the HeLa cells,

0:25:16 > 0:25:21had immediate repercussions in medical research.

0:25:21 > 0:25:24Almost immediately,

0:25:24 > 0:25:31the approach to developing a polio vaccine was available.

0:25:31 > 0:25:35And the rapid growth of HeLa cells

0:25:35 > 0:25:39allowed for the development of a polio vaccine.

0:25:42 > 0:25:44And this was only the beginning.

0:25:46 > 0:25:51HeLa cells were used to test the effects of radiation from atomic weapons.

0:25:52 > 0:25:55They were sent into space to study weightlessness.

0:25:57 > 0:26:01They've also been used to help develop therapies for Parkinson's disease,

0:26:01 > 0:26:03Aids, blood disorders

0:26:03 > 0:26:07and have played a key role in research into stem cells.

0:26:09 > 0:26:15HeLa cells have probably been the most important tool in the last half

0:26:15 > 0:26:18of the 20th century for medical research.

0:26:19 > 0:26:24The number of lives saved because of HeLa cells is in the millions.

0:26:27 > 0:26:31One small difference in the cells of Henrietta Lacks gave them their

0:26:31 > 0:26:36unique ability to carry on growing outside of her body

0:26:36 > 0:26:40and, in so doing, drive the progress of science.

0:26:41 > 0:26:45It's also a fascinating insight into what's going on inside us

0:26:45 > 0:26:47all the time.

0:26:47 > 0:26:52The fundamental process of cells dividing in a controlled way

0:26:52 > 0:26:58is the key to how our bodies grow and develop throughout our lives.

0:27:00 > 0:27:04And one of the last parts of the body to develop into its adult form

0:27:04 > 0:27:05is the skeleton.

0:27:06 > 0:27:10Our bones are far from mature at birth.

0:27:10 > 0:27:13Throughout life, a process called ossification,

0:27:13 > 0:27:16which means the replacement of cartilage with bone,

0:27:16 > 0:27:18passes through the body.

0:27:18 > 0:27:23In most of us, this whole process is complete by the time we're about 25.

0:27:23 > 0:27:27But there's one group of people in whom this process has gone awry.

0:27:29 > 0:27:33And these unusual cases are helping us understand exactly

0:27:33 > 0:27:36how this crucial part of our body forms.

0:27:42 > 0:27:48At first glance you might notice something a little out of the ordinary about Tim.

0:27:49 > 0:27:51I look a bit different, yeah.

0:27:51 > 0:27:56And it's because, inside, he hides a pretty amazing secret.

0:27:56 > 0:27:59I have super-strong bones.

0:27:59 > 0:28:02Tim has a condition that makes his bones super dense -

0:28:02 > 0:28:06in fact, 1.5 times denser than granite.

0:28:08 > 0:28:12No-one knew about it until Tim was nearly two years old.

0:28:14 > 0:28:16Initially, I had facial paralysis.

0:28:16 > 0:28:21And one half of my face, my dad mentioned one day,

0:28:21 > 0:28:24I got in the car, and I was smiling,

0:28:24 > 0:28:28but I was only smiling with half of my face.

0:28:28 > 0:28:31And they thought I was playing a prank.

0:28:33 > 0:28:36But Tim's facial paralysis didn't go away.

0:28:38 > 0:28:42Doctors performed some X-rays and found that Tim had an extremely rare

0:28:42 > 0:28:46condition, shared by just 50 people worldwide.

0:28:48 > 0:28:50I have sclerosteosis.

0:28:50 > 0:28:54It's a condition characterised by excessive bone formation.

0:28:57 > 0:29:02While sclerosteosis, or strong bones, might sound like a good thing,

0:29:02 > 0:29:06the reality is this condition put Tim's life in danger.

0:29:08 > 0:29:11As a child, his skull started to grow so thickly

0:29:11 > 0:29:15it put pressure on his cranial nerves and brain.

0:29:17 > 0:29:21If you try to alleviate that, then you will very likely die.

0:29:21 > 0:29:24They really have to cut open the skull,

0:29:24 > 0:29:27remove part of the bone, they hollow it out,

0:29:27 > 0:29:28then put it back.

0:29:28 > 0:29:32And immediately, you've got some more space for the brain.

0:29:35 > 0:29:40Doctors could treat Tim to alleviate the problems caused by the excess

0:29:40 > 0:29:44of bone, but no-one knew why he was growing extra bone in the first place.

0:29:44 > 0:29:46His condition's just so rare

0:29:46 > 0:29:49that there hasn't been much research into it.

0:29:49 > 0:29:53But then Tim's condition caught the attention of scientists who were

0:29:53 > 0:29:56studying a much more common bone disorder,

0:29:56 > 0:30:00one that seems like the polar opposite of what's happening to Tim.

0:30:01 > 0:30:05Dr Alistair Henry is a structural biologist.

0:30:06 > 0:30:10He's part of a team that studies osteoporosis,

0:30:10 > 0:30:14a loss of density in bone that leaves it weak and fragile.

0:30:14 > 0:30:19So when they came across Tim's condition, they were intrigued.

0:30:19 > 0:30:23Sclerosteosis patients, they make normal bone,

0:30:23 > 0:30:25but of a much greater density.

0:30:25 > 0:30:27So the architecture,

0:30:27 > 0:30:29the three-dimensional structure of their bone is normal.

0:30:29 > 0:30:31But much more dense.

0:30:32 > 0:30:37Dr Henry's team set out to discover what was making the bones of people

0:30:37 > 0:30:40like Tim so much denser than normal.

0:30:40 > 0:30:44They looked at the genes known to control bone growth,

0:30:44 > 0:30:48and discovered a fault in a particular gene called Sost.

0:30:48 > 0:30:51This gene makes a protein called sclerostin

0:30:51 > 0:30:54which tells our bones when to stop growing.

0:30:54 > 0:30:56And it wasn't working in Tim.

0:30:59 > 0:31:03People that have the mutation in the Sost gene, the sclerosteosis patients,

0:31:03 > 0:31:06never make sclerostin.

0:31:06 > 0:31:10Without sclerostin, Tim's body doesn't know when to stop making bone.

0:31:10 > 0:31:13So he just keeps on making more.

0:31:13 > 0:31:18This knowledge gave Dr Henry and his team an idea for a potential new

0:31:18 > 0:31:20way to treat osteoporosis.

0:31:22 > 0:31:26When we'd identified that sclerostin was the protein

0:31:26 > 0:31:28that controls bone density,

0:31:28 > 0:31:31what we wanted to do is neutralise its effect.

0:31:31 > 0:31:36We knew that if we did that we would effectively take the brake off the

0:31:36 > 0:31:38process of building new bone.

0:31:41 > 0:31:46So using this principle, Dr Henry and his team worked for several years

0:31:46 > 0:31:49to develop a new drug to treat osteoporosis.

0:31:50 > 0:31:54The next stage was to put the drug to the test.

0:31:55 > 0:31:59One such opportunity came in an unexpected place.

0:32:02 > 0:32:04Liftoff! Space shuttle Atlantis.

0:32:06 > 0:32:10In 2010, the Atlantis space shuttle blasted off

0:32:10 > 0:32:13with four astronauts on board.

0:32:13 > 0:32:18Astronauts can lose up to 30% of their bone strength in just six months

0:32:18 > 0:32:20while in space.

0:32:20 > 0:32:23And Nasa was keen to explore how to stop that loss.

0:32:25 > 0:32:29So they agreed to carry some extra, tiny passengers.

0:32:30 > 0:32:3212 mice.

0:32:33 > 0:32:36Half were given a version of the new drug,

0:32:36 > 0:32:41and after 13 days their bone density had increased,

0:32:41 > 0:32:44while the bones of the other mice had weakened.

0:32:44 > 0:32:45The drug had worked.

0:32:48 > 0:32:52And now, clinical trials involving human patients are under way.

0:32:54 > 0:32:58Tim now has some answers about his condition.

0:32:58 > 0:33:03And the millions of people suffering from osteoporosis may well have the

0:33:03 > 0:33:06promise of an effective new treatment.

0:33:06 > 0:33:10This really is amazing, for me it's fantastic news, actually.

0:33:10 > 0:33:14It really makes everything that we've gone through, all the surgery,

0:33:14 > 0:33:17all the stuff that my parents and everyone went through,

0:33:17 > 0:33:18it makes it worthwhile.

0:33:22 > 0:33:26Tim's case is helping scientists understand how our skeleton,

0:33:26 > 0:33:28the very architecture of our bodies,

0:33:28 > 0:33:31continues to grow throughout our adult life.

0:33:33 > 0:33:38The growth of cells in adults is mainly to do with maintenance and repair.

0:33:38 > 0:33:42But there's one part of the body where this process isn't so

0:33:42 > 0:33:47straightforward, where tissue can't just replace itself in the normal way.

0:33:47 > 0:33:52This is the nervous system, and the reason is to do with risk.

0:33:52 > 0:33:55If nerves just randomly replaced themselves,

0:33:55 > 0:33:59parts of the body would lose their connection with the brain,

0:33:59 > 0:34:01and this would be catastrophic.

0:34:01 > 0:34:07This also explains why spinal and nerve injuries are so hard to treat.

0:34:07 > 0:34:12But there is one kind of nerve cell that is capable of regenerating,

0:34:12 > 0:34:15as one extraordinary case shows.

0:34:20 > 0:34:25Louise Woollam is an award-winning perfume journalist and writer.

0:34:26 > 0:34:31But two years ago something happened that profoundly changed her life.

0:34:33 > 0:34:35I completely lost my sense of smell.

0:34:37 > 0:34:41Louise's sense of smell stopped working after she caught a cold.

0:34:42 > 0:34:44Maybe if you breathe in deeply and slowly...

0:34:46 > 0:34:47No.

0:34:47 > 0:34:50It's something many of us experience and it usually gets back to

0:34:50 > 0:34:53normal when the cold clears up.

0:34:53 > 0:34:54But not for Louise.

0:34:54 > 0:34:59A few days after the cold cleared up, I was at a perfume launch and I

0:34:59 > 0:35:02realised that I literally couldn't smell anything.

0:35:02 > 0:35:04It was really disconcerting.

0:35:06 > 0:35:08And then something unexpected happened.

0:35:09 > 0:35:14Louise's sense of smell started returning, but not in the way it should.

0:35:17 > 0:35:21Anything that had a smell smelt bad.

0:35:21 > 0:35:25It didn't matter whether in real life if it was a good smell

0:35:25 > 0:35:27or a bad smell, I literally experienced it

0:35:27 > 0:35:33as either a burning smell, or rotting onions, or burning meat.

0:35:33 > 0:35:35I thought I was going a bit mad.

0:35:36 > 0:35:39It's a condition called parosmia.

0:35:39 > 0:35:42Smells that used to be familiar and pleasant

0:35:42 > 0:35:44were now bizarre and repulsive.

0:35:46 > 0:35:47That's really weird.

0:35:48 > 0:35:51The worst thing was that everything that smelled bad

0:35:51 > 0:35:54tasted the way that it smelled as well.

0:35:54 > 0:35:59It's kind of a chemically... petrol sort of taste to it.

0:36:00 > 0:36:02Food was beginning to taste rotten.

0:36:02 > 0:36:07I had a bite of a chocolate biscuit and it tasted of, like, burnt leaves.

0:36:08 > 0:36:12My mum would cook Sunday lunch and it tasted like

0:36:12 > 0:36:16she'd just poured sewage over the top of it.

0:36:18 > 0:36:19As Louise was discovering,

0:36:19 > 0:36:24our sense of smell plays a vital role in the way we experience and

0:36:24 > 0:36:29understand the world around us, one we often take for granted.

0:36:30 > 0:36:33A perfume writer losing her sense of smell is actually,

0:36:33 > 0:36:36it's quite amusing and I understand...

0:36:38 > 0:36:39Sorry.

0:36:39 > 0:36:41I understand why people think it's funny...

0:36:41 > 0:36:45and most days I think it's quite funny as well because...

0:36:47 > 0:36:51..people don't really understand how important smell is

0:36:51 > 0:36:54and what an impact it can have on your daily life.

0:36:57 > 0:37:01Louise has gone from losing her sense of smell to having it come back

0:37:01 > 0:37:04but go completely awry.

0:37:04 > 0:37:06She can recognise common odours

0:37:06 > 0:37:09but nothing smells the way it should and,

0:37:09 > 0:37:12in fact, most things smell horrible.

0:37:12 > 0:37:16So clearly something highly unusual is going on

0:37:16 > 0:37:19between her nose and her brain.

0:37:20 > 0:37:24Normally, the way smell works is that we breathe in molecules

0:37:24 > 0:37:26in the air that contain odours.

0:37:26 > 0:37:30These are picked up by tiny receptors at the back of our nose,

0:37:30 > 0:37:33which are the very ends of our olfactory nerve.

0:37:34 > 0:37:38The nerve then transmits signals to the olfactory bulb

0:37:38 > 0:37:40and then deeper into the brain,

0:37:40 > 0:37:43which gives us our experience of the smell.

0:37:43 > 0:37:46It's this process that's been disrupted in Louise.

0:37:50 > 0:37:54One person who can help put it right is Chris Kelly.

0:37:54 > 0:37:58She lost her sense of smell in the same way as Louise

0:37:58 > 0:38:02and since then has spent years researching the condition.

0:38:04 > 0:38:07I imagine it a bit like a telephone exchange,

0:38:07 > 0:38:10where on the day that you lose your sense of smell,

0:38:10 > 0:38:13all the wires are pulled out and just chucked on the floor.

0:38:13 > 0:38:17And then in time some of those wires rise up

0:38:17 > 0:38:22and sort of start sticking themselves randomly into sockets

0:38:22 > 0:38:25and, of course, all the information that you get

0:38:25 > 0:38:28is cross-wired and is not...

0:38:28 > 0:38:31You're not making the right connections.

0:38:32 > 0:38:38It's a question of the brain not being able to interpret the information

0:38:38 > 0:38:41available to it because the signals are scrambled.

0:38:43 > 0:38:47So Chris made it her mission to unscramble the signals

0:38:47 > 0:38:50and retrain her brain to recognise smells again.

0:38:52 > 0:38:54Basically, smell training is simple.

0:38:54 > 0:38:58You have to engage your brain, it is brain training.

0:38:58 > 0:39:02You are building new neural pathways,

0:39:02 > 0:39:08and doing that every day exercises a part of your brain.

0:39:08 > 0:39:09It's like physiotherapy.

0:39:12 > 0:39:16Now, Chris uses her technique to help others with the same condition

0:39:16 > 0:39:18and she's working with Louise.

0:39:20 > 0:39:23Louise experienced terrible, crippling parosmia.

0:39:23 > 0:39:25And so for her, like with many parosmics,

0:39:25 > 0:39:31bad smells are just a no-go area and the best way of...

0:39:32 > 0:39:37..getting over that is to keep exposing yourself gently

0:39:37 > 0:39:41to these things that are causing so much revulsion.

0:39:42 > 0:39:47These are what most people would consider bad smells.

0:39:47 > 0:39:51Smell training is not a cure for parosmia.

0:39:51 > 0:39:55But it has been shown to have one very important effect.

0:39:55 > 0:39:57When we lose our sense of smell,

0:39:57 > 0:40:00cells in the olfactory nerve are damaged.

0:40:00 > 0:40:02I have no idea what that is.

0:40:02 > 0:40:07And this causes the olfactory bulb to shrink due to lack of use.

0:40:07 > 0:40:11But it appears that by stimulating the olfactory system,

0:40:11 > 0:40:16smell training can halt and even reverse this process.

0:40:18 > 0:40:19That is the smell of sweaty feet.

0:40:19 > 0:40:22Ah! That doesn't smell that bad. OK.

0:40:22 > 0:40:25- Would you like to smell it again? - No, not particularly.

0:40:25 > 0:40:28Not now I know what it is.

0:40:29 > 0:40:33In order to make smell training useful,

0:40:33 > 0:40:36you can't just wave it in front of your nose,

0:40:36 > 0:40:41but you have to peer down into each one of these smells and look for

0:40:41 > 0:40:42something in it.

0:40:44 > 0:40:48Smell training is making a difference for Louise.

0:40:48 > 0:40:52Now, more than half the odours she encounters do actually smell the way

0:40:52 > 0:40:56they should and she's hoping that gradually more will return.

0:40:59 > 0:41:01I don't think I'll ever smell the same way again.

0:41:01 > 0:41:05It will always be different but hopefully it'll be better.

0:41:08 > 0:41:13Thanks to the remarkable ability of the olfactory nerve to regrow,

0:41:13 > 0:41:16Louise is training her brain to smell again.

0:41:16 > 0:41:21But the brain is one part of the body that's a long way from being

0:41:21 > 0:41:24fully developed when we're born.

0:41:25 > 0:41:28It continues to adapt and change into adulthood

0:41:28 > 0:41:30as we acquire new abilities.

0:41:32 > 0:41:36And I found some fascinating cases that are helping unlock the secrets

0:41:36 > 0:41:38of this remarkable process.

0:41:39 > 0:41:44This is the hippocampus, an area of the brain associated,

0:41:44 > 0:41:48amongst other things, with an ability to navigate.

0:41:48 > 0:41:49Now, on brain scans,

0:41:49 > 0:41:53taxi drivers are found to have an increased amount of grey matter here,

0:41:53 > 0:41:58which is used for processing, and this increases the more time they spend

0:41:58 > 0:42:00behind the wheel.

0:42:00 > 0:42:03It's proof of the fact that even in adulthood,

0:42:03 > 0:42:06learning can change the structure of the brain.

0:42:06 > 0:42:11This ability to make cognitive maps is something that in most of us is

0:42:11 > 0:42:14developed by about the age of eight.

0:42:14 > 0:42:15But in some people,

0:42:15 > 0:42:20the ability to build and use these cognitive maps never fully develops.

0:42:24 > 0:42:27Anne loves to go walking in the countryside near her

0:42:27 > 0:42:29home in Calgary, Canada.

0:42:33 > 0:42:38But even a stroll through her local park can be fraught with difficulty.

0:42:38 > 0:42:40I get lost all the time.

0:42:42 > 0:42:43Even in my own neighbourhood.

0:42:46 > 0:42:51Lots of us think we have a poor sense of direction but Anne has a cognitive condition

0:42:51 > 0:42:55that means she finds it almost impossible to navigate the world

0:42:55 > 0:42:56around her.

0:42:57 > 0:43:01She can even get disorientated in her own home.

0:43:04 > 0:43:08I don't think people really understand what it's like not to

0:43:08 > 0:43:11really have any sense of direction.

0:43:12 > 0:43:17It affects my employment, it affects just daily functioning.

0:43:21 > 0:43:24Anne's condition has an impact on the entire family.

0:43:26 > 0:43:29My mom's sense of direction is nonexistent.

0:43:29 > 0:43:32It's absolutely terrible.

0:43:32 > 0:43:34When we play sports we always get lost

0:43:34 > 0:43:39and everyone knows we'll be late, so no-one wants to carpool with us.

0:43:41 > 0:43:43If Anne's going somewhere new,

0:43:43 > 0:43:46she always has to have some sort of back-up plan.

0:43:46 > 0:43:49She can walk out this door and go two blocks and not find her way back.

0:43:49 > 0:43:51It can be that bad.

0:43:52 > 0:43:57Anne does use GPS but it doesn't solve the problem entirely.

0:43:59 > 0:44:03I like the GPS that's mounted and then I can see sort of visually.

0:44:03 > 0:44:06But, you know, sometimes I'm not quite certain which turn to take.

0:44:08 > 0:44:11This isn't just a case of someone with a bad sense of direction.

0:44:11 > 0:44:14Anne can't recognise the most familiar places

0:44:14 > 0:44:20that are part of her everyday life. Even her home is a challenge.

0:44:20 > 0:44:24It sounds impossible to believe and until recently

0:44:24 > 0:44:28scientists didn't even know that this strange condition existed.

0:44:30 > 0:44:34Giuseppe Iaria is associate professor of cognitive neuroscience

0:44:34 > 0:44:37at the University of Calgary.

0:44:38 > 0:44:43He studies how our brain enables us to navigate.

0:44:43 > 0:44:48The most important ability in terms of orientation skills is the ability

0:44:48 > 0:44:50of forming mental maps.

0:44:50 > 0:44:56The ability to form a map and make use of the map for orientation

0:44:56 > 0:45:00requires a variety of complex cognitive skills.

0:45:00 > 0:45:02Attention, perception, memory,

0:45:02 > 0:45:04decision-making skills, mental imagery.

0:45:04 > 0:45:09This ability is fully developed by the age of eight to ten years.

0:45:11 > 0:45:13But in 2008,

0:45:13 > 0:45:18Professor Iaria was contacted by a woman who described how she consistently

0:45:18 > 0:45:20got lost in her own home...

0:45:21 > 0:45:24..a place she'd lived in for 20 years.

0:45:27 > 0:45:30We knew that people with neurological disorders

0:45:30 > 0:45:35or brain damage can actually have problems in terms of orientation.

0:45:35 > 0:45:40But having people without any other cognitive or neurological disorder

0:45:40 > 0:45:43getting lost every day, that was very new.

0:45:46 > 0:45:50Professor Iaria concluded that the woman had simply never developed the

0:45:50 > 0:45:53ability to orientate herself,

0:45:53 > 0:45:57a disorder that hadn't previously been recognised.

0:45:57 > 0:46:02He named it Developmental Topographical Disorientation, or DTD.

0:46:05 > 0:46:08To see if he could find anyone else with the same condition,

0:46:08 > 0:46:11he went on national radio to talk about the case.

0:46:14 > 0:46:17On the radio, when I was listening to this interview,

0:46:17 > 0:46:22there was the mention of not having an internal compass

0:46:22 > 0:46:24and it's a neurological condition.

0:46:24 > 0:46:27I thought, "I've got to get a hold of him!"

0:46:29 > 0:46:33We were really surprised by the response we got.

0:46:33 > 0:46:36Within one single year we were able to test

0:46:36 > 0:46:39and publish a scientific paper,

0:46:39 > 0:46:43with 120 individuals affected by this condition.

0:46:43 > 0:46:49Professor Iaria has asked Anne to draw a floor plan of her own home.

0:46:49 > 0:46:52And then there's the entryway.

0:46:52 > 0:46:54Most of us can visualise where the rooms are

0:46:54 > 0:46:57and transfer that mental map to paper.

0:46:57 > 0:47:01But people with DTD, like Anne, find this task impossible.

0:47:03 > 0:47:08So then is this the exit door? Is this the back door?

0:47:08 > 0:47:13So these rooms are definitely not all the same size.

0:47:13 > 0:47:16No. No, but where it's...

0:47:16 > 0:47:18The location is there, yeah.

0:47:18 > 0:47:19Yeah.

0:47:19 > 0:47:20SHE LAUGHS

0:47:23 > 0:47:27To discover why people like Anne are unable to form mental maps,

0:47:27 > 0:47:32Professor Iaria has been using an MRI scanner to look deep in their brains.

0:47:34 > 0:47:36And he's found something unusual.

0:47:38 > 0:47:39To be able to navigate,

0:47:39 > 0:47:43we mainly need two parts of the brain to work together -

0:47:43 > 0:47:48the hippocampus, where we form maps, and the prefrontal cortex,

0:47:48 > 0:47:51where we make plans and decisions.

0:47:51 > 0:47:52In patients with DTD,

0:47:52 > 0:47:57the professor found these two parts of the brain were not active at the

0:47:57 > 0:48:00same time and therefore were not in sync.

0:48:03 > 0:48:08We did compare the group of individuals with DTD with a group of

0:48:08 > 0:48:10individuals without DTD.

0:48:11 > 0:48:14The difference we found was a decreased connectivity

0:48:14 > 0:48:18between the hippocampus and the prefrontal cortex.

0:48:20 > 0:48:24This is a clue as to why Anne was getting lost all the time.

0:48:24 > 0:48:28And there are indications that this runs in the family.

0:48:28 > 0:48:33One of Anne's sisters and her aunt also show signs of having the condition

0:48:33 > 0:48:36and are now also working with Professor Iaria.

0:48:36 > 0:48:41This, and other cases, suggest the cause of the condition may be genetic.

0:48:44 > 0:48:50This is a unique opportunity to relate genetics to complex cognitive

0:48:50 > 0:48:53functions, not just to medical conditions.

0:48:56 > 0:49:02Now, Professor Iaria is working on a treatment, but it isn't a drug,

0:49:02 > 0:49:03it's a computer game.

0:49:05 > 0:49:08The player learns to navigate between different locations.

0:49:10 > 0:49:13The aim is to train the brain to form mental maps.

0:49:15 > 0:49:18Those training programmes can actually help also individuals

0:49:18 > 0:49:20who have a poor sense of direction,

0:49:20 > 0:49:24not necessarily individuals affected by DTD.

0:49:25 > 0:49:30Anne now finally understands why she finds it so difficult to navigate

0:49:30 > 0:49:32and knows she's not alone.

0:49:33 > 0:49:37Finding out that this actually is a condition,

0:49:37 > 0:49:41there was a lot of relief and consolation in that.

0:49:41 > 0:49:44What's most exciting is that this kind of treatment has the potential

0:49:44 > 0:49:47to help patients with dementia,

0:49:47 > 0:49:51who lose their ability to form mental maps later in life.

0:49:59 > 0:50:02Anne is slowly becoming able to navigate the world

0:50:02 > 0:50:06because the brain has the ability to keep changing and developing

0:50:06 > 0:50:08through our lives.

0:50:08 > 0:50:12But there are some things we're born with that are written into the very

0:50:12 > 0:50:17fabric of ourselves and simply won't change without medical intervention.

0:50:19 > 0:50:22For diseases that are caused by faulty genes,

0:50:22 > 0:50:27the Holy Grail is finding a way to try and rewrite the genetic code to

0:50:27 > 0:50:29change the DNA,

0:50:29 > 0:50:33as happened in our last, remarkable case.

0:50:36 > 0:50:39Rhys Evans has made medical history.

0:50:41 > 0:50:45The fact that he can live the normal life of a teenager is thanks to a

0:50:45 > 0:50:47ground-breaking treatment.

0:50:49 > 0:50:52He was a happy baby, putting on weight,

0:50:52 > 0:50:55he was really well, but when I stopped breast-feeding him

0:50:55 > 0:51:02then he seemed to have little coughs and colds and several chest infections.

0:51:04 > 0:51:07These frequent infections baffled doctors.

0:51:09 > 0:51:12He was given lots of antibiotics but nothing seemed to do the trick

0:51:12 > 0:51:15and I just think he was just deteriorating,

0:51:15 > 0:51:17he was losing lots of weight.

0:51:18 > 0:51:22As his condition worsened, Rhys was admitted to hospital.

0:51:22 > 0:51:26After four weeks of tests, the family received a diagnosis.

0:51:28 > 0:51:33Rhys had a rare genetic condition known as Severe Combined

0:51:33 > 0:51:35Immunodeficiency, or Scid.

0:51:36 > 0:51:40A fault in a single gene meant his immune system didn't work.

0:51:43 > 0:51:47As a boy he didn't have a functioning immune system, well,

0:51:47 > 0:51:49basically no immune system whatsoever.

0:51:49 > 0:51:54So if he went outside or got in contact with other children,

0:51:54 > 0:51:58then he could catch anything, which could be fatal for him.

0:51:59 > 0:52:02This was a life-threatening condition.

0:52:02 > 0:52:06Rhys was transferred to a purpose-built isolation unit at

0:52:06 > 0:52:08Great Ormond Street Hospital in London.

0:52:11 > 0:52:14He was moved to a very sterile room.

0:52:14 > 0:52:19We both stayed in the room with him for what must have been 11 months,

0:52:19 > 0:52:21within a very sterile environment.

0:52:23 > 0:52:27Being isolated from the outside world protected Rhys from the infections

0:52:27 > 0:52:31that most of us shrug off but could have killed him.

0:52:32 > 0:52:35To have any chance of a normal life,

0:52:35 > 0:52:38he needed a way to repair his broken immune system.

0:52:40 > 0:52:41And in the same hospital,

0:52:41 > 0:52:45Professor Adrian Thrasher and Professor Bobby Gaspar

0:52:45 > 0:52:51were researching a key part of the immune system - white blood cells.

0:52:54 > 0:52:57When we're all born, we have to fight infection.

0:52:57 > 0:52:59We have to...

0:52:59 > 0:53:05be able to live in the world and not get infections

0:53:05 > 0:53:07and we need white cells in our blood to do that,

0:53:07 > 0:53:10so that's what the white cells do, they fight infection,

0:53:10 > 0:53:12they stop us from getting coughs and colds.

0:53:12 > 0:53:15And the thing with Scid is that these children are born without

0:53:15 > 0:53:18white cells, or white cells that don't work properly.

0:53:19 > 0:53:24Magnified a thousand times, you can see the immune system at work.

0:53:24 > 0:53:26The large cells are white blood cells.

0:53:26 > 0:53:30Here, they are swallowing up some tiny green invaders,

0:53:30 > 0:53:34one of the ways they can protect us against infections and toxins.

0:53:34 > 0:53:38But Rhys' white blood cells weren't working properly.

0:53:38 > 0:53:43Before 1968, these immunodeficiencies were universally fatal.

0:53:43 > 0:53:45There was really nothing that could be done.

0:53:45 > 0:53:50In 1968 the first-ever child with Scid was treated successfully

0:53:50 > 0:53:52by bone marrow transplantation.

0:53:54 > 0:53:57White blood cells grow and develop within bone marrow,

0:53:57 > 0:54:02so a bone marrow transplant can effectively replace a faulty immune system

0:54:02 > 0:54:04with a new one.

0:54:06 > 0:54:07But there's a catch.

0:54:07 > 0:54:10For a transplant to be safe,

0:54:10 > 0:54:14the donor and recipient must have matching tissue types or the

0:54:14 > 0:54:17consequences can be fatal.

0:54:17 > 0:54:20And for Rhys, no donor could be found.

0:54:23 > 0:54:26It appeared that Rhys would have to spend the rest of his life

0:54:26 > 0:54:31in sterile conditions, locked away from the outside world.

0:54:31 > 0:54:33But there was one option -

0:54:33 > 0:54:37a ground-breaking experimental treatment.

0:54:37 > 0:54:41Instead of a transplant from another person,

0:54:41 > 0:54:45they would take some of Rhys' own cells and alter his genes to correct

0:54:45 > 0:54:48the flaw that was causing his disease.

0:54:51 > 0:54:55Adrian and I had been working on gene therapy for this particular

0:54:55 > 0:54:57condition but we hadn't treated anyone,

0:54:57 > 0:55:00we were getting ready to treat a child.

0:55:03 > 0:55:10In 2001, Rhys became the first child in the UK to receive the treatment.

0:55:10 > 0:55:13First, the doctors took a sample of stem cells from his bone marrow.

0:55:15 > 0:55:18Next, they needed to fix the genetic error.

0:55:21 > 0:55:24At the time, the only way to do this

0:55:24 > 0:55:27was with a specially engineered virus.

0:55:27 > 0:55:31It works by latching on to the surface of the stem cell and then

0:55:31 > 0:55:34injecting it with new genetic material.

0:55:36 > 0:55:38This rewrites the DNA,

0:55:38 > 0:55:41replacing the faulty gene with a corrected working copy.

0:55:44 > 0:55:46With this step complete,

0:55:46 > 0:55:50the modified stem cells were then infused back into Rhys' body.

0:55:53 > 0:55:56It was a little tiny bag and he ended up just

0:55:56 > 0:55:58having it in a little line in his arm.

0:56:00 > 0:56:05Now the hope was that the healthy stem cells would build a whole new

0:56:05 > 0:56:06immune system in Rhys' body.

0:56:09 > 0:56:12After some weeks at home, he caught a stomach bug.

0:56:14 > 0:56:19For his family and his doctors, there was now one burning question.

0:56:19 > 0:56:23Would his immune system be able to fight the infection?

0:56:24 > 0:56:28The turning point for Rhys was when his own immune system was then

0:56:28 > 0:56:33fighting the virus that was in his tummy, and that for us was, yeah,

0:56:33 > 0:56:35he is on the road to recovery.

0:56:41 > 0:56:42We'd never done this before.

0:56:44 > 0:56:47Obviously we'd been able to show what can be done in laboratories

0:56:47 > 0:56:52but to actually see it in a child, I mean, it was just fantastic.

0:56:52 > 0:56:54We knew then, it works.

0:56:54 > 0:56:57This form of treatment actually works, so it's fantastic.

0:56:59 > 0:57:04That Christmas, the team at Great Ormond Street received a special video

0:57:04 > 0:57:05of their young patient.

0:57:13 > 0:57:18Now 16, Rhys lives his life like any other teenager.

0:57:22 > 0:57:25I feel like I've won the lottery, really.

0:57:25 > 0:57:27I was a lucky number.

0:57:27 > 0:57:29I just feel like any other normal person.

0:57:31 > 0:57:34For Rhys and a whole generation of children,

0:57:34 > 0:57:38Scid no longer means living life in a sterile environment.

0:57:39 > 0:57:43You can't give any better gift than life, really,

0:57:43 > 0:57:46because you could give anybody as much money in the world as they want,

0:57:46 > 0:57:49unless they've got a life to live, there's no point, really.

0:57:52 > 0:57:56With modern medicine, we've come so far,

0:57:56 > 0:58:00but what these cases have shown me is that our bodies are constantly

0:58:00 > 0:58:02growing and developing,

0:58:02 > 0:58:06sometimes in ways we're only just beginning to understand.

0:58:08 > 0:58:13Next time, we meet an engineer who fixed his own heart,

0:58:13 > 0:58:17a girl whose body attacked her brain

0:58:17 > 0:58:21and a man who reversed a fatal illness.

0:58:21 > 0:58:23That is absolutely phenomenal.

0:58:24 > 0:58:27It's a world full of extraordinary people.