There are many kinds of scaffolds used in the field of tissue engineering, which can be divided into natural biological scaffolds and synthetic scaffolds. This paper summarizes the latest advances of research on scaffolds of skin tissue engineering and review amounts of related literatures on this field. The result shows that natural biological scaffolds can provide a better three-dimensional space for the adhesion and generation of cultured cells. These scaffolds have an extensive application in skin tissue engineering.

Objective To explore the isolation,amplification methods and adipogenic differentiation under specific culture medium of human keloid-derived precursor cell (KPC) in vitro,in order to study their possibility of being new seed cells of tissue engineering fat.Methods KPCs were isolated from human keloid tissue of 4 different patients in our hospital and were cultured in the modified L-DMEM culture medium.Their cloning efficiency and growth curve were tested.The subcultured cells were tested of the mesenchymal stem cell (MSC)-related gene expression by flow cytometry.In addition,they were cultured in H-DMEM medium (containing 1 μmol/L dexamethasone,0.5 mmol/L 3-isobutyl-1-methyl-xanthine 10 mg/L of bovine insulin,100 mmol/L indomethacin,and 10 ％ FBS)and were later observed in oil red O staining under phase contrast microscope to determine whether lipid droplets generation was formed,using skin-derived precursors (SKP) as control.Results More than 95 ％ KPC expressed many antigens of MSC,such as CD29,CD44,CD90 and CD105 while few of them expressed CD34,CD45(1.0 ％-2.5 ％).And the cells increased in size gradually after inducted the same time,changing from spindle into round or polygonal in shape.The lipid droplets were seen in 72 hours and expressed a positive rate of 78.6 ％ in Day 19 in oil red O staining while the same rate was 54.6 ％ in SKP.Conclusions Human keloid-derived precursor cells can express a variety of MSC-related surface markers without expressing hematopoietic stem cell (HSC) related markers.Furthermore,they can be differentiated into fat cells under certain conditions,which may make them as a new source of seed cells for tissue engineering fat.

Objective: To observe the uptake of ⁹⁹Tc^m-3 polyethylene glycol Arg-Gly-Asp dimer (3PRGD₂) in rat models of rheumatoid arthritis (RA), in order to provide theoretical foundation for early diagnosis of RA. Methods: The healthy female SD rats were divided into collagen induced arthritis (CIA) group (n=100), osteoarthritis (OA) group (n=20) and control group (n=20). Bovine collagen type Ⅱ emulsion was used for arthritis induction to establish CIA models. OA models were established by injection of L-cysteine and papain. Gamma imaging was performed before and 15 d, 30 d after the model establishment. The mediastinum was selected as non-target (NT) area and the target (T)/NT ratios were calculated. The serum levels of vascular endothelial growth factor (VEGF), tumor necrosis factor-α (TNF-α), α_Vβ₃ before and after the model establishment were measured. Pathological and immunohistochemical detection were performed. One-way analysis of variance, Pearson and Spearman correlation analyses were used to analyze the data. Results: There were 58 CIA models successfully established. Before the model establishment, T/NT ratios of CIA group, OA group and control group were 0.215±0.049, 0.210±0.050, 0.209±0.051, respectively (F=0.093, P>0.05). The T/NT ratios of the above three groups were 0.405±0.230, 0.223±0.045, 0.211±0.049 (F=12.601, P<0.05) 15 d post-model establishment, and those were 0.572±0.182, 0.238±0.045, 0.212±0.055 (F=65.147, P<0.05) 30 d post-model establishment. T/NT ratios of CIA group were positively correlated with the levels of serum VEGF, TNF-α, α_Vβ₃, pathological score and the levels of immunohistochemical markers (VEGF, TNF-α, α_Vβ₃, CD31, CD34; r values: 0.391-0.721, r_s values: 0.365-0.669, all P<0.05). Conclusion ⁹⁹Tc^m-3PRGD₂ can be specifically up-taken by RA lesions in rat models, thus has the potential in early synovial neovascularization imaging of RA.