No abstract

In the present study, we have established a technique to create an artificial urethra in a rat animal model by transplantation of in vitro-expanded urothelial cells onto an in vivo-prefabricated tube formation using tissue engineering methods. Urothelial cells from isogenic rats were harvested for culture. A silicon catheter was used to induce a connective tissue capsule-tube formation underneath the abdominal skin. Two weeks later, the cultivated urothelial cells were seeded onto the lumen of this tube using fibrin glue as delivery matrix. The histomorphological and immunohistochemical studies revealed a viable multilayered urothelium, lining the inner surface of the prior formed connective tissue tube-formation 4 weeks after grafting the cells. We have shown that cultured and in vitro-expanded urothelial cells can be successfully reimplanted onto a prefabricated tube-like structure using fibrin glue as a delivery matrix and native cell expansion vehicle. The results suggest that the creation of an artificial urethra may be achieved in vivo using tissue engineering methods, showing potential for urethral reconstruction and providing autologous urothelium for reconstructive surgery in the genitourinary tract.

The influence of subcutaneously injected recombinant human basic fibroblast growth factor (bFGF) on wound healing in normal (n = 20) and ischaemic (n = 28) skin tissue was investigated. Standardized wounds (5 mm2) were created on the ears of hairless mice and treated for the first 3 days after wound creation with total doses of 720 ng (n = 24) and 4050 ng (n = 24) bFGF. The bFGF had no effect on wound healing in non-ischaemic tissue. In ischaemic skin, mean(s.d.) wound surface area after treatment with 720 ng bFGF was 1.6(0.9), 0.5(0.6) and 0.1(0.3) mm2 compared with 2.8(1.0), 1.4(1.0) and 0.8(0.7) mm2 for control wounds on days 7 (P < 0.04), 10 (P < 0.03) and 13 (P < 0.04) respectively. High-dose bFGF (4050 ng) reduced the mean(s.d.) wound surface area to 2.4(0.7) and 0.8(0.7) mm2 compared with 3.9(0.6) and 2.1(0.8) mm2 for control wounds on days 7 (P < 0.006) and 10 (P < 0.02) respectively. These results suggest that bFGF may be of use for the treatment of wounds in ischaemic tissue.

Intact blood supply by microcirculation to a wounded site is an indispensable prerequisite for normal tissue regeneration. However, microvascular changes taking place in the healing process of skin wounds are not understood due to the fact that only few models allow chronic in vivo studies on skin microcirculation. Therefore, we have modified the hairless mouse ear model with the purpose of a quantitative in vivo study of microhemodynamic changes throughout the healing process. Following the creation of a standardized skin wound on the ear of the homozygous hairless mouse (hr/hr), microvessel diameters, red blood cell velocities, wet weight, and leucocyte content of the ear tissue were determined. Surface area of the wound was assessed until complete closure was achieved. By repeated measurements at identical sites over the entire healing period, a distinct pattern of microvascular changes could be observed: microvessel diameters increased to a maximum a few days after wound creation, whereas red blood cell velocities reached their highest values at a later point in time and were still elevated after complete reepithelization of the wounds. Edema and leucocyte content of the ear tissue was most prominent in the early healing phase and gradually decreased to normal values thereafter. These results demonstrate changes of the microvasculature of the hairless mouse ear to injury, which are in accordance to other more indirect studies on this topic. Therefore, we conclude that the model presented is suitable for prolonged quantitative analysis of microcirculation during normal wound healing and may be used to assess microvascular changes taking place during wound healing in pathologically altered tissue.