Objective To investigate the in vitro cytocompatibility of three-dimensional porous scaffolds of poly-D,L-lactic acid (PDLLA) and discuss the feasibility of PDLLA as a scaffold for bone tissue engineering.Methods BMSCs of the third passage were seeded on osteogenetic differentiation medium or culture medium containing 20％ volume fraction degraded liquid (PDLLA degradation liquid of 0,3,6,9,and 12 weeks) according to the random number table.Osteogenetic differentiation medium or culture medium without PDLLA was used as controls.Cell viability,cytotoxicity,and osteogenic differentiation were detected for study on cytocompatibility of PDLLA.Scanning electron microscopy was used to observe the growth of BMSCs on the surface of PDLLA scaffolds.Results PDLLA scaffolds presented no significant cytotoxic on the growth of BMSCs.PDLLA scaffolds had no negative effect on cell viability compared with the controls (t3 =-0.441,P =0.671; t6 =1.596,P =0.154; t9 =-0.492,P =0.636; t12 =-1.135,P=0.283).ALP staining and calcium nodule staining were positive and there were no significant differences in ALP and collagen Ⅰ protein quantitative detection compared with the controls.BMSCs grew well on the inner surface of the PDLLA three-dimensional porous scaffolds.Conclusion Three-dimensional porous scaffolds of PDLLA present good cytocompatibility in vitro and can be used as bone tissue engineering scaffolds for subsequent in vivo research.

Objective To investigate the therapeutic effects of nano-hydroxyapatite/polyamide 66/platelet-rich plasma com-pound(n-HA/PA66/PRP)on the recovery of rabbit femur bone defect.Methods 40 New Zealand rabbits were artificially made to be bone defect by resecting the 1 cm substantia ossea with periosteum of femur,and were divided into two groups averagely depen-ding on implanted materials:experimental group(n-HA/PA66/PRP),control group (n-HA/PA66).Every five rabbits were sacri-ficed on week 2,4,8,12,and the femur healing status was observed by X ray,histology,and immunohistochemistry.Results No rabbit was infected or died,no implantation objects dropped.Gross observation,X-ray result and histology results demonstrated that the experimental group began to have a new bone tissue at 2 weeks after the operation,with the extension of time,the experimental group new bone growth speed and the quantity was better than the control group.The Lane-Sandhu method X-ray score showed that the experimental group (6.80±2.05)points and the control group(4.20±1.30)points at 12 weeks after the operation,and there were significant differences between two groups(P <0.05).Immunohistochemistry indicated that expression intensity of Vas-cular endothelial growth factor at 2 weeks and 4 weeks were significant differences between two groups(P <0.05),but there was no significant difference at 8 weeks and 12 weeks (P >0.05).Conclusion PRP combined with n-HA/PA66 artificial bone could accel-erate the healing of bone defect,and the effect of repair of bone defect is better than that of n-HA/PA66 artificial bone in the early.

Objective To investigate histopathological and ultrastructural differences between melasma tissues and normal skin tissues around pigmented nevus. Methods Eight patients with melasma and 16 patients with facial pigmented nevus were included in this study. Two millimeter punch biopsies were taken from melasma lesions and adjacent normal skin of facial pigmented nevus. Biopsy specimens were then subjected to hematoxylin?eosin (HE) staining, Fonton?Masson staining, Verhoeff?van Gieson staining, and immunohistochemical staining with monoclonal antibodies HMB45 and NKI/beteb. Transmission electron microscopy was used to observe the tissue specimens. Semi?quantitative analysis was performed under a light microscope, and quantitative analysis by using a computerized image analysis system. Results Histopathological study revealed increased number of melanin granules mainly in the basal and prickle cell layers, sometimes in the dermis, in melasma tissues compared with normal skin tissues. Melanocytes were only observed in the epidermis of melasma tissues. Compared with normal skin tissues, melasma tissues showed no significant difference in the quantity of melanocytes, but a significant increase in the volume, staining intensity and dendrite number of melanocytes. In all of the 8 patients with melasma, mild to moderate lymphocytic infiltration was observed in the superficial dermis and around capillaries, with moderate telangiectasis in the superficial dermis. Electron microscopy revealed that there were more melanosomes in melanocytes and keratinocytes, and melanocyte dendrites extended into the dermis in melasma tissues. Conclusions Among the 8 patients, there were only two types of melasma, i.e., epidermal melasma and mixed melasma, and no dermal melasma was found. Inflammation and telangiectasis may induce or aggravate melasma.