Hypertrophic scar and keloid are common and difficult to treat diseases in plastic surgery. Results of wound healing research over the past decades have demonstrated that transforming growth factor-β (IGF-β) plays an essential role in cutaneous scar formation In contrast, fetal wounds, which heal without scarring, contain a lower level of TGF-β than adult wounds. How to translate the discovery of basic scientific research into the clinical treatment of wound scarring has become an important issue to both clinicians and basic researchers. The development of gene therapy techniques offers the potential to generically modify adult wound healing to a healing process similar to fetal wounds, and thus reduces wound scarring. This article intends to review the roles of TGF-β in the formation of wound scarring, the possible strategies of antagonizing wound TGF-β, and our preliminary results of scar gene therapy, which show that wound searring can be significantly reduced by targeting wound TGF-β.

Endothelial ceils (TEC3 cells) derived from mouse embryonic stem (ES) cells were used as seed cens to construct blood vessels. Tissue engineered blood vessels were made by seeding 8×106 smooth muscle cells (SMCs) obtained from rabbit arteries onto a sheet of nonwoven polyglycolic acid (PGA) fibers, which was used as a biodegradable polymer scaffold. After being cultured in DMEM medium for 7 days in vitro, SMCs grew well on the PGA fibers, and the ceI1-PGA sheet was then wrapped around a silicon tube, and implanted subcutaneously into nude mice. After 6～8 weeks, the silicon tube was replaced with another silicon tube in smaller diameter, and then the TEC3 cells (endothelial cells differentiated from mouse ES cells) were injected inside the engineered vessel tube as the test group. In the control group only culture medium was injected. Five days later, the engineered vessels were harvested for gross observation, histological and immunohistochemical analysis. The preliminary results demonstrated that the SMC-PGA construct could form a tubular structure in 6～8 weeks and PGA fibers were completely degraded. Histological and immunohistochemical analysis of the newly formed tissue revealed a typical blood vessel structure, including a lining of endothelial cells (ECs) on the lumimal surface and the presence of SMC and collagen in the wall. No EC lining was found in the tubes of control group. Therefore, the ECs differentiated from mouse ES cells can serve as seed cells for endothelinm lining in tissue engineered blood vessels.

Tissue engineering started in late 1980s and is now well established and progressing rapidly in Western developed countries. However, the development of tissue-engineering research in China remains relatively unknown to the international society of tissue engineering. Although involved in all areas of tissue-engineering research, including the creation of new scaffold materials, in vitro studies of seed cells, application of growth factors, and modification of seed cells and scaffold materials, China has put special emphasis on tissue construction in large mammalian animals in order to establish a solid scientific basis for clinical application of engineered tissues. To provide a closer view of tissueengineering research in China. this article reviews our experience in tissue construction and tissue repair using immunocompetent animals such as sheep, pig, and dog as well as hen and rabbit. The engineered tissues include bone, cartilage, tendon, skin, blood vessels, cornea, and peripheral nerves.