Objective To study the mechanism of dermal fibroblasts as a feeder layer to support the growth of human keratinocytes. Methods Human dermis fibroblasts were isolated and cultured and then treated with mitomycin-C. The expression of type Ⅰand type Ⅲ precollagen mRNA and relevant protein in feeder layer were examined by RT-PCR and Immunohistochemistry. KCs were cultured both on FB and NIH3T3 feed layer as control, the adhering numbers and the time of fusion were recorded. Results RT-PCR showed an increase of type Ⅰprecollagen mRNA in FB feeder layer as compared with that of normal fibroblasts (P

Objective To optimize human acellular dermal matrix(ADM) and evaluate its biological characters. Methods Human skin was treated with hypertonic saline followed by NaOH maceration(group A), hypertonic saline followed by sodium dodecyl sulfate (SDS) detergent(group B) or Dispase Ⅱ followed by Triton X-100(group C), the resulting ADM were sectioned, and then were stained by special immunohistochemistry method. The cytotoxicity of them were evaluated by methyl thiazolyl tetrazolium (MTT) colorimetry and then cell compatibility was analyzed by cell culture;The optimized ADM resulted was choosen for use. Fibrablasts(FBs)were transfected with adenovirus vector encoding green fluorescent protein gene(Ad-GFP)and the growth of them on the optimized ADM was observed by fluorescent microscopy. Results Collagen and elastic fibers can still be observed in three kinds of ADM. The cells in dermis can be disintegrated both in group A and C, but not in group B. The cytotoxicity scores of the ADM prepared in group A and B were grade 0 or grade 1, while that of group C was more than grade 1.The ADM prepared by NaCl-NaOH maceration had good biocompatibility. There was statistical difference in adhering number of NIH3T3 cells in group A and B. NIH3T3 cells grew well in group A and the resulted ADM was optimized. FBs transfected with Ad-GFP grew well in the optimized ADM. Conclusion The ADM prepared by NaCl-NaOH maceration was a good tissue engineering biomaterial with a little cytotoxicity and rich in resouce.

Objective To construct novel 3-D composite bionic network and evaluate the histocompatibility . Meth?ods The novel 3-D composite bionic network was prepared from chitosan, hydroxyapatite, gelatin and pectin in certain ra?tio by biomimtic approach, which was co-cultured with MC3T3-E1. The cell compatibility was studied by using inverted phase contrast microscope, routine paraffin section staining, scanning electron microscopy and F-DA staining. The resultant scaffold material was implanted into the dorsal subcutaneous space of SD rats. The histocompatibility, blood vessel capabili?ties and the degradation of the material were observed 2, 4, 8 and 12 weeks after surgery. Results The structure of novel 3-D composite bionic network was three-dimensional and porous. The cells attached on scaffolds attached and grew well with polygonal or fusiform form. It was found that inflammatory reactions were alleviated gradually in the early stage . There was an increasing angiogenesis at late stage. Materials degraded and absorbed more slowly. Conclusion The present study sug?gests that the novel 3-D composite bionic network has good histocompatibility with easy vascularization, and will be a candi?date scaffold for bone tissue engineering.

BACKGROUND:Polyvinyl alcohol (PVA) hydrogel with similar porous structure and mechanical properties to the natural cartilage is very suitable for the repair of articular cartilage. However, the pure PVA hydrogel after lyophilization wil be accompanied by the shrinkage of the polymer network and the col apse of the pores, leading to the inhomogeneous performance of the material even in the state of re-swel ing. Addition of the active polymer wil increase the cel adhesion ability of PVA hydrogel. OBJECTIVE:To construct PVA/lota-carrageenan (l-CA) composite materials with different mass fractions of l-CA and evaluate the biocompatibility with vascular endothelial cel s. METHODS:PVA/l-CA composite films with different contents of l-CA were fabricated and then co-cultured with vascular endothelial cel s. Attachment, proliferation and morphological changes of vascular endothelial cel s on the composite were observed by scanning electron microscope and MTT assay to evaluate its biocompatibility. PVA/l-CA three-dimensional scaffold with different contents of l-CA were constructed, and hemolysis experiment was conducted according to the biological evaluation standards of medical devices, and the porosity and pore size were observed using scanning electron microscope. RESULTS AND CONCLUSION:In vitro experimental results showed that the addition of l-CA could significantly increase the biological activity of PVA hydrogel, and promote the cel attachment and proliferation on the scaffold. The hemolysis rate of each experimental group was less than 5%(the accepted safety standard), suggesting that the composite materials were in accordance with the standard of medical devices for hemolysis experiment. These findings indicate that the composite scaffolds with 20%-30%l-CA possess the pore size suitable for cel growth and proliferation and the porosity beneficial for transportation of nutrients and metabolites, which can serve as an excel ent scaffold for tissue engineering.

Objective::To explore the effects of the biomimetic network membrane prepared by chitosan/gelatin/pectin on the proliferation and mineralization of mesenchymal stem cells (MSCs) , and to evaluate its feasibility of constructing tissue engineering bone.Methods:Chitosan, gelatin and pectin were made into a new biomimetic network membrane in a certain ratio by biomimetics.The experiment was divided into control group (MSCs+conventional medium) , material group (MSCs+network membrane+conventional medium) and material+OS group (MSCs+network membrane+OS medium) .The cell morphology was observed by inverted phase contrast microscope;the growth and secretion of extracellular matrix of the MSCs were observed under scanning electron microscope (SEM) .The proliferation of cells was determined by MTT assay (The MSCs were divided into negative control group and material group, and they were cultivated with blank medium and medium including materials) .The expression of calcium in MSCs was detected by Alizarin Red staining.Real-time polymerase chain reaction (RT-PCR) was used to determine the expression levels of osteocalcin (OC) mRNA and osteopontin (OPN) mRNA in the MSCs.Results:The network membrane was semitransparent thin film.The MSCs were short shuttle and clustered under inverted phase contrast microscope.After cultured for 7d, the MSCs were shuttle;after cultured for 14d, the number of MSCs was increased, with pseudo feet on the membrane;after cultured for21d, the MSCs clustered with a lot of neo-formed extracellular matrix.The MTT results showed that there was no significant difference in the proliferation level of MSCs between material group and negative control group (P＞0.05) .The Alizarin Red staining results showed that the MSCs in the network membrane were dyed orange red.The RT-PCR results showed that the expression levels of OC mRNA in the MSCs in material group and material+OS group were lower on the 7th and 14th days, but on the 21th day, the expression levels were significantly increased and reached the peak;the expression level of OC mRNA in the MSCs in material group was significantly increased on the 7th day, and the expression level reached the peak on the 14th day, then fell slightly on the 21th day;compared with control group, the expression levels of OC mRNA and OPN mRNA in the cells in material group and material+OS group at different time points were significantly increased (P＜0.01) , but there were no significant differences between material group and material+OS group (P＞0.05) .Conclusion:Chitosan/gelatin/pectin biomimetic network membrane has good biocompatibility, and MSCs can grow and proliferate well on the membrane.The membrane can induce the MSCs to express mineralization-related genes and proteins without inducers.

Objective: To investigate the effect of cartilage tissue engineering scaffold PVA/ι-CA on the biological behavior of the ATDC-5 cells,and to evaluate its feasibility on constructing tissue engineering cartilage. Methods:The polyvinyl alcohol (PVA)and carrageenan were used to make the composite scaffold material PVA/ι-CA according to a certain proportion by physical blending technology and repeated freezing thawing method,and the porosity and pore size of PVA/ι-CA were detected.The ATDC-5 cells were seeded into the composite scaffold and its growth was observed; the expressions of collagen type Ⅱ in the ATDC-5 cells were tested by immunohistochemical staining and immunofluorescence staining; the morphology of the ATDC-5 cells was confirmed by Toluidine blue staining.The growth and secretion of extracellular matrix of the ATDC-5 cells were observed under scanning electron microscope (SEM);the proliferative rates of ATDC-5 cells in composite scaffold materials in negative control group (added with DMEM culture media)and experimental group (added with DMEM contain scaffold)were determined by MTT assay.The composite scaffolds were implanted subcutaneously in the SD rats.The histocompatibility and vascularization in vivo of the composite scaffolds were evaluated.Results:The average porosity of cartilage tissue engineering scaffold PVA/ι-CA was (86.88±3.88)%,and the average pore size was 20-40 μm.The HE staining results showed that the ATDC-5 cells grew well with the polygon and plumpness morphology. All the samples were stained positive for collagen type Ⅱ by immunohistochemistry and immunofluorescence staining,which verified the normal phenotype of chondrocytes on the scaffolds. All the sample were stained positive for toluidine blue staining,which verified ECM deposition of the ATDC-5 cells on the scaffolds.The number of the positive cells was significantly increased with the prolongation of time.After cultured for 7 d,few of the ATDC-5 cells presented polygonal;after cultured for 14 d,the ATDC-5 cells distributed more densely,and contacted with each other on the scaffold;after cultured for 21 - 28 d,the ATDC-5 cells filled the interconnected pores of the scaffolds,synthesizing a significant amount of neo-formed ECM.The proliferation of ATDC-5 cells in PVA/ι-CA grew fast during 7-14 d,and it became slow during 21-28 d;the difference was not statistically significant compared with control group (P >0.05).The subcutaneous implantation results showed the inflammatory reactions were slight at the early stage and eviated gradually,there was an increasing angiogenesis at the late stage,and the degradation and absorption of the meterial were slight.Conclusion:PVA/ι-CA composite material will be an ideal material for the cartilage tissue engineering.