SLIVERS of skin have been stretched to twice their size in a week using a robotic bioreactor that is akin to a medieval rack. The technique could increase the size, viability and availability of skin grafts for treating burns and wounds.
The technique could increase the size and availability of skin grafts for treating burns
At present, skin grafts can be expanded by making cuts in them to create a mesh, or by inserting balloons under the graft once it has been attached to the body. These gradually expand, stretching the overlying skin. But skin meshes heal unevenly and balloons are painful, take months to expand fully and leave scars.
To try to improve on this, Sang Jin Lee of the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina, took foreskin donated after circumcision and placed it between vices inside a bioreactor, a vessel that bathes the skin in nutrients to encourage cell growth and division. The vices were controlled by a computer and could be set to move apart at specific times.
The researchers found that the best method was to stretch the skin at hourly intervals, leaving it to produce new cells in the meantime, then stretching it again. By doing this they were able to elongate the skin by 20 per cent a day, which after five days resulted in an intact strip that was twice as long as the original. Tests of the stretched skin showed that its general structure was maintained and that its thickness and pore size were almost identical to the starting tissue (Tissue Engineering Part A, DOI: 10.1089/ten.tea.2008.0195).
Lee says they have since added extra vices to stretch skin lengthways and widthways at the same time. The team has also stretched samples of human abdominal skin and pig thigh skin, demonstrating that the technique has the potential to work on a variety of skin types. However, Iain Hutchinson, a surgeon at St Bartholomew's Hospital in London points out that the researchers have yet to show that the grafts "take" when transplanted.
Lee is now testing how quickly a graft can be stretched without tearing. Speed could be important if a large graft needs to be rushed to a burns victim.
The technique could increase the size and availability of skin grafts for treating burns
At present, skin grafts can be expanded by making cuts in them to create a mesh, or by inserting balloons under the graft once it has been attached to the body. These gradually expand, stretching the overlying skin. But skin meshes heal unevenly and balloons are painful, take months to expand fully and leave scars.
To try to improve on this, Sang Jin Lee of the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina, took foreskin donated after circumcision and placed it between vices inside a bioreactor, a vessel that bathes the skin in nutrients to encourage cell growth and division. The vices were controlled by a computer and could be set to move apart at specific times.
The researchers found that the best method was to stretch the skin at hourly intervals, leaving it to produce new cells in the meantime, then stretching it again. By doing this they were able to elongate the skin by 20 per cent a day, which after five days resulted in an intact strip that was twice as long as the original. Tests of the stretched skin showed that its general structure was maintained and that its thickness and pore size were almost identical to the starting tissue (Tissue Engineering Part A, DOI: 10.1089/ten.tea.2008.0195).
Lee says they have since added extra vices to stretch skin lengthways and widthways at the same time. The team has also stretched samples of human abdominal skin and pig thigh skin, demonstrating that the technique has the potential to work on a variety of skin types. However, Iain Hutchinson, a surgeon at St Bartholomew's Hospital in London points out that the researchers have yet to show that the grafts "take" when transplanted.
Lee is now testing how quickly a graft can be stretched without tearing. Speed could be important if a large graft needs to be rushed to a burns victim.
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