ABSTRACT
BACKGROUND:Recent studies have shown that poly-L-lactic acid (PLLA) polymer has good biocompatibility and can be directly involved in human metabolism without any side effects, which is a polymer material that can be used as bioscaffolds. OBJECTIVE:To explore the biocompatibility of PLLA. METHODS:The moisture absorption rate of colagen composite and PLLA was detected. Cel morphology observation was carried to detect the growth state of C3H10T1/2 cels that grew in normal HDMEM medium, HDMEM medium+dimethyl sulfoxide, HDMEM medium+colagen composite extract, HDMEM medium+PLLA extract for 72 hours. MTT kit was used to detect the relative proliferation rate of the C3H10T1/2 cel lines that grew in the above-mentioned media and the toxicity evaluations were based on the material toxicity criteria. Hemolysis degree was measured in rabbit blood samples containing normal saline, distiled water, PLLA extract and colagen composite extract. The alergic reaction and pyrogen reaction in rabbits were observed through injection of normal saline, distiled water, PLLA extract and colagen composite extract viathe ear vein. Colagen composite and PLLA were respectively implanted subcutaneously into the rabbits, and after 4 weeks, the levels of interleukin-10 and interleukin 23 in serum were detected. RESULTS AND CONCLUSION: The moisture absorption rates per unit area and per unit mass of colagen composite material were lower than those of PLLA synthetic materials (P < 0.05). C3H10T1/2 cels grew wel in the PLLA extract, with a higher relative growth rate and lower cytotoxicity (grade I). Compared with the colagen composite materials, the PLLA synthetic materials had a lower hemolysis ratio and less inflammatory reactions (P < 0.05); and there were no alergic reaction and pyrogen reaction. These findings indicate that the PLLA scaffold materials for burned skin have good absorbing fluid performance and biocompatibility.
ABSTRACT
BACKGROUND:The regenerated celulose membrane has good moisture absorption and mechanical strength as wel as good biodegradability, but its toughness is poorer. Studies have shown that the dry film of regenerated celulose membrane has a poor elongation rate that is less than 15%. OBJECTIVE: To prepare the compound regenerated celulose membrane/colagen membrane, and to test its mechanical properties, sweling properties, moisture permeability and water retention. METHODS:Using sodium periodate oxidation method, the 2,3-dialdehydecelulose/colagen membrane was prepared. Infrared spectroscopy and scanning electron microscope were used to observe the morphological structure, and test its mechanical properties, sweling properties, moisture permeability and water retention. Meanwhile, the regenerated celulose membrane and 2,3-dialdehydecelulose membrane served as controls. Fibroblasts from logarithmic phase mouse embryos were seeded onto the 2,3-dialdehydecelulose/colagen membrane, and after 1, 3, 5 days, MTT method was used to detect cel proliferation. RESULTS AND CONCLUSION:Infrared spectra showed that the colagen was cured to the surface of 2,3-dialdehydecelulose membrane. Under the scanning electron microscopy, the 2,3-dialdehydecelulose/ colagen membrane had loose porous structure, with a porosity of 93.4%. The mechanical properties, sweling rate and moisture permeability of the 2,3-dialdehydecelulose/colagen membrane were significantly stronger than those of the 2,3-dialdehydecelulose membrane and regenerated celulose membrane (P < 0.05). However, there was no difference in the water retention rate among the three groups. Mouse embryonic fibroblasts tightly adhered to the surface of regenerated celulose/colagen membrane, and presented a proliferative trend. These findings indicate that the 2,3-dialdehydecelulose/colagen membrane has good mechanical properties, sweling property, moisture permeability, water retention, and cytocompatibility.
ABSTRACT
Abstract BACKGROUND: As an emerging technology, tissue-engineered skin has great application prospects. Keratinocyte growth factor (KGF) is proved to promote the proliferation of epidermal cels. OBJECTIVE: To evaluate the effect and characteristics of tissue-engineered skin carrying KGF nanocapsules in repairing skin defects of nude mice. METHODS:(1) The acelular dermal matrix loading KGF (KGF-ADM) was constructed. The human epidermal stem cel population and fibroblasts were captured and cultivated, and then identified. Epidermal stem cels were cultivated on the KGF-ADM and their growth was observed. The tissue-engineered skin loading KGF nanocapsules was transplanted onto the ful-skin defects on the back of nude mice compared with a blank group without keratinocyte growth factor nanocapsules and a control group with skin autograft. In 2, 4 and 6 weeks after transplantation, the contraction and histological healing of the skin were observed respectively. Then anti-human keratin 10-FITC and β1-integrin-Cy3 immunofluorescence were applied to detect the origin, growth and differentiation of stem cels in the epidermis and dermis. RESULTS AND CONCLUSION: The epidermal stem cel population grew wel on the surface of KGF-ADM and attached tightly. There were smal round epidermal stem cels and polygonal terminaly-differentiated cels, which presented with partly cloning growth and a tendency of merging into pieces. The results of tissue-engineered skin with KGF nanocapsules in repairing the skin defects were better than those of the blank group and the control group in 2, 4 and 6 weeks after transplantation. The transplanted skin could fuse with adjacent skin completely, but stil showed some contraction. Under the microscope, they showed good epidermis with layers and normal keratose stratum, and meanwhile, there were stil some β1-integrin+ cels at 8 and 10 weeks, which were epidermal stem cels or transient amplifying cels identified by immunofluorescence. These findings indicate that the tissue-engineered skin carrying KGF nanocapsules has good outcomes in repairing skin defects of nude mice, which is better than common tissue-engineered skin without KGF nanocapsules and autogeneous skin transplantation.
ABSTRACT
BACKGROUND:The proliferation and differentiation of hair-folicle-generating stem cels are influenced by the joint action of their own genes and external signals. Wnt/β-catenin signaling pathway plays an important role in the development of hair folicles, but the detailed mechanisms are not yet clear. OBJECTIVE:To investigate, with interruption of keratinocyte growth factor and lithium chloride, the function and the interrelationship of Wnt/β-catenin signaling pathway with other signal factors when human hair-folicle-generating stem cels differentiate into dermal papila cels or epidermal cels. METHODS: Hair-folicle-generating stem cels were isolated from the bulge and cultivated. Then the growth curve of hair-folicle-generating stem cels was tested and formed in order to observe the cellproliferation ability cultivated at different densities (1×106/L, 1×107/L, 1×108/L, 1×109/L) at each time. Immunoflurorescene staining was performed to identify hair-folicle-generating stem cels and their differentiated cels. Lithium chloride (0, 0.5, 1.5, 10, 25 mmol/L individualy) and keratinocyte growth factor(0, 10, 25, 50, 100 μg/L individualy) were used to induce the differentiation of hair-folicle-generating stem cels. Then, we contrasted and analyzed the proliferation ability in each case, thereby investigating the most appropriate concentration of keratinocyte growth factor and lithium chloride to spur the differentiation of hair-folicle-generating stem cels. At days 3, 5, 7 and 9, we tested and compared the mRNA expressions of β-catenin, APC, GSK-3β, Axin and Lef1 from cels in control group, 10 mmol/L lithium chloride group and 10 μg/L keratinocyte growth factor group. RESULTS AND CONCLUSION:Isolating cultured hair-folicle-generating stem cels stil had a great reproductive activity and multi-lineage potential even after various times subculturein vitro. With higher lithium chloride concentration, the proliferation ability of hair-folicle-generating stem cels declined; while it increased when keratinocyte growth factor concentration increased. In K-SFM medium which contained lithium chloride, the transformation of hair-folicle-generating stem cels was obvious, showing distinct differences among groups. Especialy, the level ofβ-catenin reached the peak when lithium chloride > 10 mmol/L. However, in K-SFM medium which contained keratinocyte growth factor, hair-folicle-generating stem cels differentiated into epidermal cels and the level of β-catenin changed slightly. We found that, while spurring the differentiation of hair-folicle-generating stem cels, lithium chloride could activate Wnt/β-catenin signal pathway and inhibit GSK-3β, a vital component of degradation compound. This facilitated β-catenin expressing in the cytoplasm to translocate into the nucleus. As a result, the transcription of target gene increased. It is the most appropriate concentration to spur hair-folicle-generating stem cels differentiation when lithium chloride level is > 10 mmol/L, but the proliferation ability declines correspondingly. Keratinocyte growth factor, which can facilitate hair-folicle-generating stem cels differentiated into epidermal cels, is a key factor to accelerate proliferation ability and migration of hair-folicle-generating stem cels, re-epithelialization and healing of wound. The mechanisms of hair-folicle-generating stem cels oriented differentiation induced by lithium chloride and keratinocyte growth factor are activating Wnt/β-catenin signal pathway, inducing change of β-catenin expression, and activating the transcription of target gene related to Wnt/β-catenin signaling pathway .