| Background The injury of articular cartilage has been a common disease of joint surgery.Once cartilage is damage,it has limited potential of self-repairing. Many attempts have been made to repair defects;however,the long term results were not satisfactory.Autologous chondrocyte implantation(ACI)is an effect ways treatment of articular cartilage deflects.However,patients may suffer from harvesting cartilage and second stage operation.It has reported that mesenchymal stem cells(MSCs)can be differentiating into chondrocytes for the reason of their capacity of self-renewal and multilineage differentiation.Bone marrow(BM)is the major source of MSCs;however,aspiration of BM involves invasive procedures.Since the application of embryonic stems cells(ESCs)were restricts for ethical concerns.Searching for a feasible way to obtain fetal pluripotent stem cells has generated a great deal of interest from researchers.It has been reported that MSCs could be isolated from various tissues,including adipose tissue, synovium,amniotic fluid,placental,cord blood and umbilical cord tissues. Among those,umbilical cord may be ideal sources due to their accessibility, painless procedures to donors,and promising sources for cell therapy.Thus, umbilical cord should be focused on as an alternative source of MSCs.Methods(1)To analysis of composition of umbilical cord,histochemistry, immunohistochemistry and quantitation on glycosaminoglycans(GAGs)and type â…¡collagen were made to study the characterist of tissue structure.(2)To obtain adherent cell,Wharton's jelly of umbilical cord diced into small fragments then culture with DMEM;the second way was digest with collagenase.The MSCs were passaged,drawing growth curve and cryopreservation and thawing.Surface antigen of MSCs was detected by flow cytometry.Cartilage markers were detected by histochemistry,immunohistochemistry and RT-PCR analysis.(3)To analyze the chondrogeneic differentiation of Wharton's jelly MSCs,the cells were cultured with chondrogenic medium and a pellet culture system combined rotary cell culture system(RCCS)was used.Cartilage markers,quantitation of GAGs and typeâ…¡collagen were also detected.(4)After protein extraction of adherent mammalian cells of Wharton's jelly MSCs,chondrogenic MSCs and articular chondrocyte,protein quantitation was made,then cytokines level of each sample detection as protocol of RayBio(R)human cytokine antibody array kit.Results(1)Wharton's jelly is abundant and contains significant amounts of hyaluronic acid,mesenchymal cells and GAGs immobilised in an insoluble collagen fibril.(2)The duration of confluent of primary culture cells was 3-5d with collagenase digestion which is better than micro mass culture.The result of flow cytometry detection showed MSCs of Wharton's jelly express CD44,CD 105 and CD271;the expression of HLA-ABC was positive and the cryopreservation and thawing showed no singnificant effect on immunophenotype;the MSCs weakly express chondrocyte marker,and positive express of Sox-9 and Col-2al. (3)When Wharton's jelly MSCs were culultured with chondrogenic meidum, cartilage related ECM synthesis and secretion.When high density MSCs with pellet and RCCS chondrogeic induction,an opaque with glistening non-scoffold cartilage were formed.Paraffin sections of these pellets showed that cartilage matrix was synthesized.GAGs and typeâ…¡collagen content significantly increased after chondrogenic induction.(4)The expression levels of cytokines, chemotatic factors and bone and cartilage related factors from MSCs and their differentiated chondrocyte were similar to adult articular cartilage cells.Other factors such as tumor-inhibiting factor and nerve growth factors were also expressed in those cells.Conclusion(1)Wharton's jelly is abundant and contains significant amounts of collagen fibril and GAGs,and ECM of Wharton's jelly is similar to cartilage. (2)The MSCs of umbilical cord resource is both amplification,and no ethics problems.The MSCs of umbilical cord with the characteristic of MSCs and doesn't different into hematopoietic cells.(3)The umbilical cord MSCs express chondrocyte marker and with characteristic of pre-chondrocyte and maybe the newly stem cells for tissue engineering of cartilage.Non-scaffold tissue engineering cartilage block was formed with high density cells number culture and bioreactor chondrogenic induction,and maybe a new method of fabricating tissue engineering cartilage in vitro.(4)The human cytokine expression spectrum of Wharton's jelly MSCs and their differentiated cartilage cells were similar to adult articular cartilage cells,which showed that Wharton's jelly MSCs and their differentiated cartilage cells were similar to articular cartilage cells,can be used as new source stem cells for tissue engineering of cartilage.
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