Three-Dimensional Reconstitution of Nerve Blood Vessel Units on Damaged Trachea and Bronchial Stump Using Hybrid-Transplantation of Skeletal muscle-derived stem cells and Bioabsorbable Polyglyconate Felt
A hybrid transplantation system using skeletal muscle-derived multipotent stem cells (Sk-MSCs) and bioabsorbable polyglyconate (PGA) felt was applied to coverage of the tracheal large-hole and the bronchial stump model, for the purpose of nerve-blood vessel supplementation to prevent tissue necrosis. Sk-MSCs were obtained from green-fluorescent transgenic (GFP-Tg) mouse muscles after 5 days of expansion culture. Experimental tracheal large-hole and bronchial stump following pneumonectomy were prepared using C57BL6N mice, and damaged portions were covered with PGA felt, which was then impregnated with expanded Sk-MSCs. At 2-10 weeks after transplantation, fluorescent-stereoscopy and immunohistochemical analysis were performed in order to confirm the in vivo behavior of engrafted GFP+ cells. Acceleration of nerveblood vessel formation capacity was quantified and compared between the hybrid and solo PGA felt transplantation group. RTPCR analysis of nerve-blood vessel growth, tropic, and trophic factors for re-isolated engrafted GFP+ tissue was also performed in order to confirm paracrine effects after transplantation. Acceleration of blood vessel formation was observed in both the hybrid and solo PGA transplantation groups; however, nerve formation capacity was significantly (10-fold) higher in the hybrid group. Co-transplanted GFP+ cells were stably held in the PGA area, thus confirming the prevention of unnecessary cell diffusion. Donor-derived GFP+ cells actively differentiated into vascular smooth muscle and endothelial cells, and Schwann cells and perineurium, and supported nerveblood vessel network formation. In addition, re-isolated engrafted GFP+ cells continued to express various essential nerve-blood vessel factors, confirming the prolonged biological adjuvant effects of this hybrid system. These effects were consistently observed in both the tracheal and bronchial stump damaged model. Therefore, use of the present Sk-MSC and PGA felt hybrid transplantation system is a possible treatment for the prevention of postpneumonectomy bronchial stump fistula, as an adjuvant for attributive nerve-blood vessel supplementation.