Hoxb13 knockout adult skin exhibits high levels of hyaluronan and enhanced wound healing.

In contrast to adult cutaneous wound repair, early gestational fetal cutaneous wounds heal by a process of regeneration, resulting in little or no scarring. Previous studies indicate that down-regulation of HoxB13, a member of the highly conserved family of Hox transcription factors, occurs during fetal scarless wound healing. No down-regulation was noted in adult wounds. Here, we evaluate healing of adult cutaneous wounds in Hoxb13 knockout (KO) mice, hypothesizing that loss of Hoxb13 in adult skin should result in enhanced wound healing. Tensiometry was used to measure the tensile strength of incisional wounds over a 60-day time course; overall, Hoxb13 KO wounds are significantly stronger than wild-type (WT). Histological evaluation of incisional wounds shows that 7-day-old Hoxb13 KO wounds are significantly smaller and that 60-day-old Hoxb13 KO wounds exhibit a more normal collagen architecture compared with WT wounds. We also find that excisional wounds close at a faster rate in Hoxb13 KO mice. Biochemical and histochemical analyses show that Hoxb13 KO skin contains significantly elevated levels of hyaluronan. Because higher levels of hyaluronan and enhanced wound healing are characteristics of fetal skin, we conclude that loss of Hoxb13 produces a more "fetal-like" state in adult skin.

Coincidence of connective tissue growth factor expression with fibrosis and angiogenesis in postoperative peritoneal adhesion formation.

PURPOSE: To investigate the relationship between connective tissue growth factor (CTGF) and fibrosis and angiogenesis in postoperative peritoneal adhesion formation. METHODS: Adhesions were performed in 35 rats by creation of a peritoneal patch. Animals were sacrificed at 7 different time-points over 3 weeks. Adhesions and uninjured peritoneum from all animals were assessed by Northern blotting for CTGF and collagen-I mRNA and by immunohistochemistry for CTGF localization, degree of fibrosis and angiogenesis. RESULTS: Persistent adhesions formed in all animals. CTGF and collagen-I mRNA were increased in adhesions compared to uninjured peritoneum (p < 0.05 for both). The temporal expression pattern depicted delayed peak levels of collagen-I mRNA with increasing tendency for both transcripts at the end of the observation period. Fibrosis within adhesions correlated positively with time after surgery (r = 0.85; p < 0.001) and showed typical signs of chronic tissue fibrosis at later time points. Angiogenesis was detected in adhesions but not in uninjured peritoneum (p = 0.001) and coincided with the spatial and temporal expression of CTGF protein in fibroblasts and vascular endothelial cells. CONCLUSIONS: The co-expression of CTGF with increasing fibrosis and angiogenesis in postoperative peritoneal adhesions suggests a role for CTGF as critical molecule in fibrous adhesive disease and target for future adhesion prevention.

Expression of connective tissue growth factor in intra-abdominal adhesions.

PURPOSE: Connective tissue growth factor stimulates fibroblast proliferation and extracellular matrix deposition in many fibrotic disorders. The aim of our study was to determine the expression pattern of connective tissue growth factor in postoperative intra-abdominal adhesions. METHODS: Adhesions were created in 46 Sprague-Dawley rats by complete dissection and resuturing of a peritoneal patch 2 cm in diameter, lateral from the midline incision. Animals were killed at postoperative Days 3, 6, 9, 12, 15, 18, and 21 and the adhesions scored on a scale of 0 to 5. Tissue samples from adhesion areas and from uninvolved peritoneum were evaluated by Northern and Western blotting for temporal connective tissue growth factor mRNA and protein expression, respectively. Immunohistochemical analysis was performed for connective tissue growth factor localization. RESULTS: Adhesions formed in all animals after surgery and were confined to the peritoneal patches. Adhesion formation increased across time, with significant correlation between adhesion scores and postoperative days (r = 0.329, P = 0.026). Connective tissue growth factor mRNA concentrations were significantly elevated in adhesion tissue throughout the three-week period when compared with normal peritoneum (P = 0.012); peak levels occurred between Days 6 and 15. Western blots demonstrated connective tissue growth factor protein expression in adhesions from Days 6 to 21, in contrast to negligible bands in normal peritoneum. Fibroblasts within the adhesive tissue, but not in uninjured peritoneum, stained positive for connective tissue growth factor by immunohistochemistry. CONCLUSIONS: We have demonstrated a specific temporal and spatial expression pattern for connective tissue growth factor in intra-abdominal adhesions during a three-week postoperative time course. According to what is known about the functional role of connective tissue growth factor in fibrogenesis, our findings warrant further investigations addressing a causal relationship between this growth factor and fibrous adhesion formation.