[An experimental study on biocompatibility of Bio-oss collagen with cultured bone marrow stromal cells].

PURPOSE: To study the biocompatibility of Bio-oss collagen with cultured bone marrow stromal cells. METHODS: The bone marrow stromal cells (BMSCs) of rhesus monkey were cultured with Bio-oss collagen in vitro. Cell attachment was observed with laser confocal microscope. Cell proliferation rates were assessed with MTT assay. ALP activity was also detected. The data was statistically analyzed with SAS6.12 software package for Student's t test. RESULTS: The rhesus BMSCs could attach to the surface of Bio-oss collagen. In cell proliferation rates, there was no significant difference between the control group and experimental group at 2-day and 5-day(P>0.05). However, at 8-day, the difference was significant (P<0.05). For ALP activity, there was no significant difference among different time point (P>0.05). CONCLUSIONS: The Bio-oss collagen has good biocompatibility with rhesus BMSCs, and could be used to repair periodontal bone defects as a biomaterial in tissue engineering.

[The experimental study of creating a new rat scarring model by inserting absorbable gelatin sponge into rats' excisional wounds].

OBJECTIVE: To explore the possibility of creating a rat new scar model by inserting gelatin sponge into rat excisional wounds. METHODS: Two full-thickness wounds were created in each of total 49 SD rats. In the Experimental group (n = 19), a regular incisional wound (1 cm) was created on the left side, and an excisional wound of 1.0 cm x 0.2 cm was created on the right side with a gelatin sponge inserted. In control 1 group (n = 15), an excisional wound with sponge insertion was created on both sides of rats. In control 2 group (n = 15), two excisional wounds were created on both sides, and only one side wounds were inserted with a sponge. Animals were sacrificed at various time points for different examinations. RESULTS: The wound/scar width increased 4 - 11 times in inserted wounds than in regular incisional wounds (P < 0.01), with an obvious delay of epithelialization. No difference in wound/scar width was found in both sides of wounds of control 1 group at various locations. In contrast to the linear scar of sponge-inserted wounds, contracted and irregular scar was found in non-inserted wounds of control 2 group. CONCLUSIONS: Gelatin sponge insertion can create a thick linear scar in rat wounds, and thus provides a new model for scar research.

[Experimental study on constructing small-caliber artery by tissue engineering approach].

OBJECTIVE: To investigate the possibility of constructing small-caliber artery by means of tissue engineering. METHODS: Cell-PGA mixtures were made by separately seeding 1 x 10(7) smooth muscle cells and 5 x 10(6) endothelial cells isolated from neonate umbilicus onto PGA scaffold, the cell-PGA constructs were wrapped around a silicone tube before its implantation subcutaneously to nude mice and the mice were sacrificed in 2 and 6 weeks. The tissue engineered artery (TEA) were examined both grossly and immunohistochemically. RESULTS: The gross appearance of TEA was similar to that of the natural counterparts; histologic and immunohistochemical analyses of the neoformed tissues revealed a typical artery structure, including the presence of EC at the luminal surface and the presence of SMC and collagen in the wall. CONCLUSION: TEA with histology similar to natural vessel can be constructed by tissue engineering.

[Inhibiting scar formation in rat cutaneous wounds by blocking TGF-beta signaling].

OBJECTIVE: TGF-beta plays a key role in wound scarring. This study explored the possibility of using gene therapy to inhibit wound scarring by blocking TGF-beta signaling. METHODS: In vitro, human normal dermal fibroblasts were infected with recombinant adenoviruses of truncated TGF-beta receptor II (tTGF-betaRII, 100 pfu/cell) and beta-galactosidase (beta-gal, 100 pfu/cell), and their effects on regulating TGF-beta1 gene expression were analyzed by Northern blot. For gene therapy, beta-gal and tTGF-betaRII viruses (1 x 10(9) pfu)were injected intradermally at left and right side of dorsal skin of newborn Sprague-Dawley rats (n = 15) respectively. A full-thickness incisional wound (0.5 cm long) was created at the injection sites of each rat 2 days post-injection. An incisional wound was similarly created in the middle part of the dorsal skin of tTGF-betaRII transgenic mice (n = 5) and control mice (n = 5). Wound tissues of rats and mice were harvested at various time points post-wounding for histological and immunohistochemical analysis. Scar area in tissue section was measured by Image-Pro Plus software. RESULTS: Over-expression of tTGF-betaRII markedly reduced TGF-beta1 gene expression in dermal fibroblasts. Adenovirus mediated gene expression in skin reached a peak level 2 - 3 days post-injection, and decreased gradually at 5 - 7 days. Two weeks post-wounding, histology and quantitative analysis demonstrated that relative scar area in the wounds of transgenic mice and control mice were 136,969.8 +/- 66,339 and 474,641.6 +/- 227,396 respectively, the scar area of transgenic wounds was 29 percent of control area (P < 0.05). In all rats, wounds transfected with tTGF-betaRII gene healed with much less scarring (relative scar area 128,311.2 +/- 36,764.6) than control wounds (251,189.1 +/- 62,544.7) of the same rat, with a 45% reduction of scar area in average (P < 0.001). In addition, the tTGF-betaRII expression also decreased inflammation and TGF-beta1 production in treated wounds, and promoted the repair of panniculus muscle in treated wounds. CONCLUSIONS: Adenovirus mediated over-expression of tTGF-betaRII can block TGF-beta signaling and inhibit wound scarring, and thus can serve as a gene therapy strategy to control wound scarring.