HLA class I and class II allelic genotypes were determined in 371 unrelated individuals and 309 members of 81 families inhabiting the central Japan area. A total of 20 HLA-A alleles, 16 HLA-Cw alleles, 38 HLA-B alleles, 27 HLA-DRB1 alleles, 15 HLA-DQB1 alleles and 12 HLA-DPB1 alleles were detected. By the two-, three-, four-, five- and six-locus allelic association analyses extracted from the HLA-A to -DPB1 locus, 26 HLA-Cw-B haplotypes, 25 HLA-DRB1-DQB1 haplotypes, 42 HLA-Cw-B-DRB1 haplotypes, 37 HLA-Cw-B-DRB1-DQB1 haplotypes, 29 HLA-A-Cw-B-DRB1-DQB1 haplotypes and 21 HLA-A-Cw-B-DRB1-DQB1-DPB1 haplotypes with the frequencies of higher than 0.005 were recognized. Among 19 HLA-B alleles with the high allele frequencies (above 0.007), 9 HLA-B alleles, B*0702, B*1301, B*3701, B*3901, B*4006, B*4403, B*5201, B*5901 and B*6701 were found to be tightly associated with single HLA-Cw alleles. Most of HLA-DRB1 alleles showed strong associations with single HLA-DQB1 alleles, but DRB1*0802 and DRB1*1401 were associated with two different DQB1 alleles. Extended haplotypes carrying infrequent class I alleles with the allele frequencies of lower than 0.007 were defined by family studies. Gene frequencies and haplotypic associations within the entire HLA classical loci elucidated at the high resolution (four-digital) allelic level will provide useful information on anthropology, marrow donor registry, legal medicine and disease-association studies.

Our findings indicate that PRP can promote the therapeutic potential of MDSCs expressing BMP-4 and sFlt1 for AC repair (4 weeks post-treatment) by promoting collagen synthesis, suppressing chondrocyte apoptosis and finally by enhancing the integration of the transplanted cells in the repair process.

These findings could contribute to the development of biological treatments that aid in the healing of skeletal muscle after injury.

We recently reported that the ruptured regions of the human anterior cruciate ligament (ACL) contained vascular-derived stem cells, which showed the potential for high expansion and multilineage differentiation. In this study, we performed experiments to test the hypothesis that ACL-derived CD34 + cells could contribute to tendon-bone healing. ACL-derived cells were isolated from the rupture site of human ACL by fluorescenceactivated cell sorting. Following ACL reconstruction, immunodeficient rats received intracapsular administration of either ACL-derived CD34 + cells, nonsorted (NS) cells, CD34 -cells, or phosphate-buffered saline (PBS). We also performed in vitro cell proliferation assays and enzyme-linked immunosorbent assays for vascular endothelial growth factor (VEGF) secretion. We confirmed the recruitment of the transplanted cells into the perigraft site after intracapuslar injection by immunohistochemical staining at week 1. Histological evaluation showed a greater area of collagen fiber formation and more collagen type II expression in the CD34 + group than the other groups at the week 2 time point. Immunostaining with isolectin B4 and rat osteocalcin demonstrated enhanced angiogenesis and osteogenesis in the CD34 + group at week 2. Moreover, double immunohistochemical staining for human-specific endothelial cell (EC) and osteoblast (OB) markers at week 2 demonstrated a greater ability of differentiation into ECs and OBs in the CD34 + group. Microcomputerized tomography showed the greatest healing of perigraft bone at week 4 in the CD34 + cell group, and the failure load of tensile test at week 8 demonstrated the greatest biomechanical strength in the CD34 + group. Furthermore, the in vitro studies indicated that the CD34 + group was superior to the other groups in their cell proliferation and VEGF secretion capacities. We demonstrated that ACL-derived CD34 + cells contributed to the tendon-bone healing after ACL reconstruction via the enhancement of angiogenesis and osteogenesis, which also contributed to an increase in biomechanical strength.