Invited review: mesenchymal progenitor cells in intramuscular connective tissue development.

The abundance and cross-linking of intramuscular connective tissue contributes to the background toughness of meat, and is thus undesirable. Connective tissue is mainly synthesized by intramuscular fibroblasts. Myocytes, adipocytes and fibroblasts are derived from a common pool of progenitor cells during the early embryonic development. It appears that multipotent mesenchymal stem cells first diverge into either myogenic or non-myogenic lineages; non-myogenic mesenchymal progenitors then develop into the stromal-vascular fraction of skeletal muscle wherein adipocytes, fibroblasts and derived mesenchymal progenitors reside. Because non-myogenic mesenchymal progenitors mainly undergo adipogenic or fibrogenic differentiation during muscle development, strengthening progenitor proliferation enhances the potential for both intramuscular adipogenesis and fibrogenesis, leading to the elevation of both marbling and connective tissue content in the resulting meat product. Furthermore, given the bipotent developmental potential of progenitor cells, enhancing their conversion to adipogenesis reduces fibrogenesis, which likely results in the overall improvement of marbling (more intramuscular adipocytes) and tenderness (less connective tissue) of meat. Fibrogenesis is mainly regulated by the transforming growth factor (TGF) ß signaling pathway and its regulatory cascade. In addition, extracellular matrix, a part of the intramuscular connective tissue, provides a niche environment for regulating myogenic differentiation of satellite cells and muscle growth. Despite rapid progress, many questions remain in the role of extracellular matrix on muscle development, and factors determining the early differentiation of myogenic, adipogenic and fibrogenic cells, which warrant further studies.

Recurrence after anatomic resection versus nonanatomic resection for hepatocellular carcinoma: a meta-analysis.

The impact of anatomic resection (AR) as compared to non-anatomic resection (NAR) for hepatocellular carcinoma (HCC) as a factor for preventing intra-hepatic and local recurrence after the initial surgical procedure remains controversial. A systematic review and meta-analysis of nonrandomized trials comparing anatomic resection with non-anatomic resection for HCC published from 1990 to 2010 in PubMed and Medline, Cochrane Library, Embase, and Science Citation Index were therefore performed. Intra-hepatic recurrence, including early and late, and local recurrence were considered as primary outcomes. As secondary outcomes, 5 year survival and 5 year disease-free survival were considered. Pooled effects were calculated utilizing either fixed effects or random effects models. Eleven non-randomized studies including 1,576 patients were identified and analyzed, with 810 patients in the AR group and 766 in the NAR group. Patients in the AR group were characterized by lower prevalence of cirrhosis, more favorable hepatic function, and larger tumor size and higher prevalence of macrovascular invasion compared with patients in the NAR group. Anatomic resection significantly reduced the risks of local recurrence and achieved a better 5 years disease-free survival. Also, anatomic resection was marginally effective for decreasing the early intra-hepatic recurrence. However, it was not advantageous in preventing late intra-hepatic recurrence compared with non-anatomic resection. No differences were found between AR and NAR with respect to postoperative morbidity, mortality, and hospitalization. Anatomic resection can be recommended as superior to non-anatomic resection in terms of reducing the risks of local recurrence, early intra-hepatic recurrence and achieving a better 5 year disease-free survival in HCC patients.

Developmental changes of carcass composition, meat quality and organs in the Jinhua pig and Landrace.

The present study was aimed to compare the developmental changes of carcass composition, meat quality characteristics and organ weight in pigs of different breeds. Six pigs (sex balance) of each breed were slaughtered at 35, 80 and 125 days of age, respectively. The carcass was chilled and the left carcass side was dissected into bone, lean meat, fat and skin; additionally, organ weight and meat quality parameters were observed. Carcasses of the Jinhua pig were lighter (P < 0.001), contained less lean meat percentage (P < 0.01) and more carcass fat percentage (P < 0.05) than did carcasses of the Landrace. L*-values were lower in Jinhua pigs than in Landrace at 125 days of age (P < 0.05), but the Jinhua pig had higher a*-values compared with Landrace at the age of 80 days (P < 0.01) and 125 days (P < 0.01), respectively. In addition, Jinhua pigs showed lower colour scores (P < 0.05), higher intramuscular fat (IMF) percentage (P < 0.05), less marbling scores (P < 0.05) and lower drip loss (P < 0.05) than Landrace. For organ weight, Jinhua pigs had higher relative heart weight at the age of 80 days (P < 0.05) and 125 days (P < 0.001), and higher relative liver weight at 125 days of age (P < 0.01) than that of Landrace. In addition, the relative kidney weight was heavier (P < 0.001) in the Jinhua pig than in the Landrace during the whole experiment. These results indicated that developmental changes of carcass composition, meat quality parameters and organ weight displayed breed differences. Jinhua pigs were fatter than Landrace but the former had better quality characteristics in the meat.