Autologous tissue patch rich in stem cells created in the subcutaneous tissue

AIM:To investigate whether we could create natural autologous tissue patches in the subcutaneous space for organ repair. METHODS: We implanted the following three types of inert foreign bodies in the subcutaneous tissue of rats to produce autologous tissue patches of different geometries:(1) a large-sized polyvinyl tube(L = 25 mm,internal diameter = 7 mm) sealed at both ends by heat application for obtaining a large flat piece of tissue patch for organ repair;(2) a fine polyvinyl tubing(L = 25 mm,internal diameter = 3 mm) for creating cylindrically shaped grafts for vascular or nerve repair; and(3) a slurry of polydextran particle gel for inducing a bladder-like tissue. Implantation of inert materials was carried out by making a small incision on one or either side of the thoracic-lumbar region of rats. Subcutaneous pockets were created by blunt dissection around the incision into which the inert bodies were inserted(1 or 2 per rat). The incisions were closed with silk sutures,and the animals were allowed to recover. In case of the polydextran gel slurry 5 m L of the slurry was injected in the subcutaneous space using an 18 gauge needle. After implanting the foreign bodies a newly regenerated encapsulating tissue developed around the foreign bodies. The tissues were harvested after 4-42 d of implantation and studied by gross examination,histology,and histochemistry for organization,vascularity,and presence of mesenchymal stem cells(MSCs)(CD271+CD34+ cells). RESULTS: Implanting a large cylindrically shaped polyvinyl tube resulted in a large flat sheet of tissue that could be tailored to a specific size and shape for use as a tissue patch for repairing large organs. Implanting a smaller sized polyvinyl tube yielded a cylindrical tissue that could be useful for repairing nerves and blood vessels. This type of patch could be obtained in different lengths by varying the length of the implanted tube. Implanting a suspension of inert polydextran suspension gave rise to a bladder-like tissue that could be potentially use