Objective To explore the biocompatibility of poly(lacticacid/glycolic acid/asparagic acid-co-polyethylene glycol) biomaterials (PLGA-ASP-PEG) and biological behaviors of cultured marrow stroml stem cells (MSCs) combined with this new type of scaffold in tissue engineering. Methods The PLGA-ASP-PEG tri-block copolymers were obtained through bulk ringopening copolymerization method.MSCs were isolated from the bone marrow of 4 week old New Zealand rabbits. The 3rdgeneration MSCs were cultured combining with PLGA-ASP-PEG in vitro, while cells cultured in PLGA as control group. The cell adhesion rate and the adhesivepower were examined by conventional precipitation method and micropipette aspiration technique respectively. The morphological features were studied by scanning electron microscope. The proliferation behavior of the cells was analyzed by MTT assay. The cell cycle, proliferation index, DNA index and apoptosis of the cells were detected by flow cytometry. The synthesis of protein and collagen were examined by Coomassie Brilliant Blue dyes and 3H-Proline incorporation test. Results The MSCs adhered and grew well on the surface of the biomaterial PLGA-ASP-PEG. The powers of cell adhesion, proliferation and protein and collagen synthesis of the cells were all significantly higher than those of PLGA group (P＜0.05), but the apoptosis rate was significantly lower than that of PLGA group (P＜0.05). The DNA indexes showed the cells of both PLGA-ASP-PEG group and PLGAgroup were normal diploid cells. Conclusion PLGA-ASP-PEG showedgood biocompatibilityand the biological properties improved greatly compared with the PLGA scaffold materials. These results demonstrated that the promise of PLGAASPPEG canbe used as an ideal scaffold material for construction of tissue engineered bone to restore bone defects in bone tissue engineering．
PEGylating is an effective way for prolonging the half-time period and decreasing the immunogenicity of protein drugs. With experiments of single factor, it was proved that the optimal processes for PEGylating the fused protein of LL-37 and interferon (IFN)-α2a were:PEG molecular weight was 5 000, fused protein concentration was 0.6 mg/mL, the mole ratio of protein to mPEG5000-SS was 1:10, the reaction temperature was 4℃, and the pH was 9.0, respectively. With orthogonal experiments, we proved that the influential order of 3 main factors is:the fused protein concentration > the mole ratio of protein and mPEG5000-SS > pH and the optimal conditions were the fused protein concentration as 0.6 mg/mL, the mole ratio of protein and mPEG5000-SS as 1:10, pH as 8.8. Under these optimal conditions, the average rate of PEGylated protein with 3 times parallel experiments was 86.98%. After PEGylated, the interferon activity and antimicrobial activity of fused protein could be remained higher than 58% and 97%, respectively.
ObjectiveAdopting poly-L-lactic/glycolic acid (PLGA) and polyethylene glycol (PEG) as the material to fabricate PLGA/PEG electrospun polymer membrane by electrospinning technology. And to study its preventive effect on postoperative intraperitoneal adhesion of rat.MethodsPLGA and PEG were mixed at the ratio of 19∶1(M/M), then dissolved in organic solvent. The PLGA/PEG electrospun polymer membrane was prepared by electrospinning technology, and then the gross observation and scanning electron microscope observation were taken. Fifty-four Sprague Dawley rats (weighing, 180-200 g), were randomly divided into 3 groups. The rats in control group (n=6) were left intact. The rats in model group (n=24) and PLGA/PEG group (n=24) were treated with the method of mechanical injury of the cecal serosa in order to establish the intraperitoneal adhesion models; then the PLGA/PEG electrospun polymer membrane was used to cover the wound in PLGA/PEG group, but was not in the model group. The intraperitoneal adhesion in PLGA/PEG group and model group were observed at 3 days, 1 week, 2 weeks, and 8 weeks after operation, and the adhesion degree was assessed according to the self-generated standard. The degradation of PLGA/PEG electrospun polymer membrane was also observed in PLGA/PEG group. At each time point, the rats were harvested for histological observation. All the above indexes were compared with the control group.ResultsUsing the electrospinning technology, PLGA/PEG electrospun polymer membrane was prepared successfully. PLGA/PEG electrospun polymer membrane was white and opaque, with soft texture. Scanning electron microscopy observation showed that PLGA/PEG electrospun polymer membrane was mainly composed of disorderly staggered fibers, with microporous structure. All rats survived to the end of the experiment. Gross observation showed that PLGA/PEG electrospun polymer membrane gradually degraded after implantation in vivo, and the adhesion degree in PLGA/PEG group was significantly lower than that in model group (P<0.05), but it had not yet reached to the level of the control group (P<0.05). Histological observation showed that the proliferation of cecal fibrous connective tissue was slower in PLGA/PEG group than in model group, and adhesion severity significantly decreased, only with a small amount of inflammatory cell infiltration. Nevertheless, it was not up to the level of the control group.ConclusionPLGA/PEG electrospun polymer membrane can effectively prevent postoperative intraperitoneal adhesion of rat, and has good biodegradability.
Objective To explore the construction of a canine model of vascularized allogeneic spinal cord transplantation (vASCT) and preliminarily evaluate its therapeutic efficacy for spinal cord injury (SCI). Methods Sixteen female Beagle dogs aged 8-12 months were randomly selected, with 8 dogs serving as donors for the harvesting of spinal cord tissue with a vascular pedicle [dorsal intercostal artery (DIA) at the T10 level and accompanying vein]. The remaining 8 dogs underwent a 1.5-cm-length spinal cord defect at the T10 level, followed by transplantation of the donor spinal cord tissue for repair. Polyethylene glycol (PEG) was applied to both ends to spinal cord graft. Using a random number table method, the dogs were divided into an experimental group (n=4) and a control group (n=4). The experimental group received immunosuppressive intervention with oral tacrolimus [0.1 mg/(kg∙d)] postoperatively, while the control group received no treatment. The operation time and ischemia-reperfusion time of two groups were recorded. The recovery of hind limb function was estimated by Olby score within 2 months after operation; the motor evoked potentials (MEP) was measured through neuroelectrophysiological examination, and the spinal cord integrity was observed through MRI. ResultsThere was no significant difference in the operation time and ischemia-reperfusion time between the two groups (P>0.05). All dogs survived until the completion of the experiment. Within 2 months after operation, all dogs in the control group failed to regain the movement function of hind limbs, and Olby scores were all 0. In the experimental group, the movement and weight-bearing, as well as walking abilities of the hind limbs gradually recovered, and the Olby scores also showed a gradually increasing trend. There was a significant difference between the two groups from 3 to 8 weeks after operation (P<0.05). Neuroelectrophysiological examination indicated that the electrical signals of the experimental group passed through the transplanted area, and the latency was shortened compared to that at 1 month after operation (P<0.05), showing continuous improvement, but the amplitude did not show significant improvement (P>0.05). The control group was unable to detect any MEP changes after the operation. MRI examination showed that the transplanted spinal cord in the experimental group survived and had good continuity with normal spinal cord tissue, while no relevant changes were observed in the control group. ConclusionThe vASCT model of dogs was successfully constructed. This surgical procedure can restore the continuity of the spinal cord. The combination of tacrolimus anti-immunity is a key factor for the success of transplantation.