The girl whose skin never heals
Sohana Collins has never known a day without pain. The 11-year-old has a rare genetic disorder that means her skin blisters and tears at the slightest friction.
It also affects her internal skin, which means her mouth and oesophagus blister. This makes swallowing difficult and eating painful - her food has to be liquidised. The condition is caused by the lack of a protein that holds the skin together.
About 8,000 people in the UK have epidermolysis bullosa (EB).
Sohana has a particularly severe form known as recessive dystrophic epidermolysis bullosa (RDEB), which gets progressively worse. Most patients develop malignant skin cancer before their mid-30s.
I have met Sohana several times over recent months and she has always been uncomplaining about her condition, with a great sense of fun.
On one occasion she chatted to me animatedly about the Harry Potter books while she sat on the sofa next to her mum, with a thick scarf covering her entire face.
The scarf was to shield her eyes from light. RDEB periodically strips the protective UV layer from the cornea - meaning she must stay in the dark for several days. Any light caused an intense pain, but she was keeping herself busy by listening to the audio books about JK Rowling's schoolboy wizard.
Bone marrow cells
Twice a day she must endure her dressings being changed. Her mother has to prick each blister otherwise they keep growing until large sheets of skin fall off leaving a bleeding raw patch which is reluctant to heal.
"There is no moment of any minute of any day that she is not in some pain somewhere on her body," says her mother, Sharmila Nikapota. "To have to prick her skin every day and make her cry is horrible. It's definitely the worst part of my day and of hers."
The prospect for patients such as Sohana has been bleak until recently. Now she is one of 10 patients testing a new cell therapy at London's Great Ormond Street Hospital.
It involves an infusion of donated bone marrow cells, the hope being these will migrate to her damaged skin and encourage healing.
The trial is lead by Prof John McGrath, head of the genetic skin disease group at King's College London, whose team discovered that a subset of bone marrow cells could promote skin repair.
"We are not sure how these specialist bone marrow cells work, but we think that once infused into the body they respond to distress signals from the damaged skin - which are effectively asking the body to heal them," he says.
Three months after the infusion, I returned to see Sohana. Although her skin was still very damaged, parts of it seemed much improved.
Sohana's family and the medical team agree that her skin is blistering less and the wounded areas are healing better. Changing her dressings is taking less time than before. She has even put on weight.
Sohana agrees: "I think things have got a lot better and my skin is a lot less red and sore and a lot less itchy as well."
There is always a danger of wish fulfilment in such situations - it is understandable that everyone is desperate for signs of improvement. Prof McGrath is cautiously optimistic, but won't be able to make a clear judgement until all the data from the 10 patients is reviewed next year.
The treatment is not a cure but it may buy time for Sohana whilst other research avenues are explored.
"We expect the anti-inflammatory and better wound healing effects of these cells will last for between six and nine months, perhaps even a year. At that stage we can perhaps do this treatment again or maybe we'll be moving on to an even more effective treatment" says Prof McGrath.
There are several options including using tissue-matched cells for therapy - probably some kind of bone marrow transplant.
It can be difficult to find suitable bone marrow donors and doctors say they cannot justify going down that route until they can show that the initial trial is successful.
Several bone marrow transplants have already been carried out in the United States, leading to permanent and significant skin improvements. But three of the first 10 patients died, so researchers are trying to establish how to make the treatment safer.
Scientists at King's are also investigating gene therapy - with the aim of correcting the faulty protein in affected patients.
Rare diseases often struggle to get research funds. Sohana's parents were determined to accelerate progress so they set up a charitable fund to raise money that goes directly to fund clinical trials.
They have been extraordinarily successful. The Sohana Research Fund has raised more than £2m. It has some high-profile supporters, the actor Damien Lewis is a patron.
"The future really is looking a lot brighter for patients with EB - there is huge momentum going towards the search for better treatments and maybe even a cure," says Prof McGrath.
"The benefits of the research could apply more widely for patients with damaged skin, such as those with ulcers, wounds and burns. "
Sohana has three younger sisters, none of whom is affected by EB. "For the first time in her life Sohana's skin has been getting better rather than progressively worse," says her mother. "We know that time is running out for her so we just hope that a treatment will come along that will allow her to lead a normal life."