Co-transplantation of neural stem cells and Schwann cells within poly (L-lactic-co-glycolic acid) scaffolds facilitates axonal regeneration in hemisected rat spinal cord / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Various tissue engineering strategies have been developed to facilitate axonal regeneration after spinal cord injury. This study aimed to investigate whether neural stem cells (NSCs) could survive in poly(L-lactic-co-glycolic acid) (PLGA) scaffolds and, when cografted with Schwann cells (SCs), could be induced to differentiate towards neurons which form synaptic connection and eventually facilitate axonal regeneration and myelination and motor function.</p><p><b>METHODS</b>NSCs and SCs which were seeded within the directional PLGA scaffolds were implanted in hemisected adult rat spinal cord. Control rats were similarly injured and implanted of scaffolds with or without NSCs. Survival, migration, differentiation, synaptic formation of NSCs, axonal regeneration and myelination and motor function were analyzed. Student's t test was used to determine differences in surviving percentage of NSCs. One-way analysis of variance (ANOVA) was used to determine the differences in the number of axons myelinated in the scaffolds, the mean latency and amplitude of cortical motor evoked potentials (CMEPs) and Basso, Beattie & Bresnahan locomotor rating scale (BBB) score. The χ(2) test was used to determine the differences in recovery percentage of CMEPs.</p><p><b>RESULTS</b>NSCs survived, but the majority migrated into adjacent host cord and died mostly. Survival rate of NSCs with SCs was higher than that of NSCs without SCs ((1.7831 ± 0.0402)% vs. (1.4911 ± 0.0313)%, P < 0.001). Cografted with SCs, NSCs were induced to differentiate towards neurons and might form synaptic connection. The mean number of myelinated axons in PLGA + NSCs + SCs group was more than that in PLGA + NSCs group and in PLGA group ((110.25 ± 30.46) vs. (18.25 ± 3.30) and (11.25 ± 5.54), P < 0.01). The percentage of CMEPs recovery in PLGA + NSCs + SCs group was higher than in the other groups (84.8% vs. 50.0% and 37.5%, P < 0.05). The amplitude of CMEPs in PLGA + NSCs + SCs group was higher than in the other groups ((1452.63 ± 331.70) µV vs. (428.84 ± 193.01) µV and (117.33 ± 14.40) µV, P < 0.05). Ipsilateral retransection resulted in disappearance again and functional loss of CMEPs for a few days. But contralateral retransection completely damaged the bilateral motor function.</p><p><b>CONCLUSIONS</b>NSCs can survive in PLGA scaffolds, and SCs promote NSCs to survive and differentiate towards neurons in vivo which even might form synaptic connection. The scaffolds seeded with cells facilitate axonal regeneration and myelination and motor function recovery. But regenerating axons have limited contribution to motor function recovery.</p>

Effect of poly(DL-lactide-co-glycolide) on scar formation after glaucoma filtration surgery / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Glaucoma filtering surgery (GFS) is the most common procedure performed in the treatment of glaucoma. Although antiscarring agents help prevent postsurgical scarring and improve glaucoma surgical outcomes, they may be associated with an increased incidence of severe and potentially blinding complications. Poly(DL-lactide-co-glycolide) (PDLLA/GA) is a bioresorbable polymer, which can be prepared with a large range of physical, mechanical, and biological properties and has been widely used in medicine, including as an absorbable suture and a drug carrier and especially as a scaffold in tissue engineering. This study aimed to evaluate the effect of PDLLA/GA on scar formation after glaucoma filtration surgery (GFS).</p><p><b>METHODS</b>Forty-eight New Zealand white rabbits were divided into two groups randomly and GFS was performed on the right eye of each. PDLLA/GA membranes were put under the sclera flap for evaluation. GFS with no membrane inserted served as control. Clinical evaluations of intraocular pressure (IOP) and the presence of a filtration bleb were performed at intervals (3 days, 1, 2, 4, 8, 12, 20, and 24 weeks) postoperatively. At each time point, three eyes per group were excised to observe histological changes such as inflammation and scar formation and the expression of collagen type IV, proliferating cell nuclear antigen (PCNA), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1). The expression of connective tissue growth factor (CTGF) mRNA was determined by reverse transcription-polymerase chain reaction.</p><p><b>RESULTS</b>The lower IOP level and an effective bleb were maintained for a long time after GFS in the PDLLA/GA group. The histological analysis showed less inflammation and scar formation, weaker expression of collagen type IV and PCNA, more intense MMP-9 and TIMP-1, slightly elevated ratio of MMP-9 and TIMP-1, and a smaller increase in CTGF mRNA postoperatively in the PDLLA/GA group but less than the control group (P < 0.05).</p><p><b>CONCLUSION</b>PDLLA/GA membranes may be promising for preventing fibrosis after GFS.</p>

Functional recovery following traumatic spinal cord injury mediated by a unique polymer scaffold seeded with neural stem cells and Schwann cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The most important objective of transplant studies in the injured spinal cord has been to provide a favorable environment for axonal growth. Moreover, the continuing discovery of new grafts is providing new potentially interesting transplant candidates. Our purpose was to observe the morphological and functional repair effects of the co-transplantation of neural stem cell (NSC), Schwann cells (SCs) and poly lactide-co-glycolide acid (PLGA) on the spinal cord injury of rats.</p><p><b>METHODS</b>A scaffold of PLGA was fabricated. NSCs and SCs were cultured, with the NSCs labeled with 5-bromodeoxyuridine, and the complex of NSC/PLGA or NSC + SCs/PLGA were constructed. Thirty-six Wistar rats were randomly divided into three groups: group A (transplantation of PLGA), group B (transplantation of NSC/PLGA) and group C (transplantation of NSC + SCs/PLGA). The 3 mm length of the right hemicord was removed under the microscope in all rats. The PLGA or the complex of PLGA-cells were implanted into the injury site. Basso-Beattie-Bresnahan (BBB) locomotion scores, motor and somatosensory evoked potential of lower limbs were examined to learn the rehabilitation of sensory and motor function at 4 weeks, 8 weeks, 12 weeks and 24 weeks after injury. All the recovered spinal cord injury (SCI) tissues were observed with HE staining, immunohistochemistry, and transelectronmicroscopy to identify the survival, migration and differentiation of the transplanted cells and the regeneration of neural fibres at 4 weeks, 8 weeks, 12 weeks and 24 weeks after injury.</p><p><b>RESULTS</b>(1) From 4 weeks to 24 weeks after injury, the BBB locomotion scores of cell-transplanted groups were better than those of the non-cell-transplanted group, especially group C (P < 0.05). The amplitudes of the somatosensory evoked potential (SEP) and motor-evoked potential (MEP) were improved after injury in groups B and C, but the amplitude of SEP and MEP at 4 weeks was lower than that at 12 weeks and 24 weeks after injury. Compared with group B, the amplitude of SEP and MEP in group C was improved. The amplitude of SEP and MEP was not improved after injury in group A. (2) HE staining revealed the volume of the scaffold decreased and the number of cells in the scaffold increased. Newly-grown capillaries also could be seen. Immunohistochemistry staining showed the transplanted NSCs could survive and migrate until 24 weeks and they could differentiate into neurons and oligodendrocytes. The regenerated axons were observed in the scaffold-cell complex with transelectronmicroscopy. The above manifestations were more extensive in group C.</p><p><b>CONCLUSIONS</b>The transplanted NSC can survive and migrate in the spinal cord of rats up to 24 weeks after injury, and they can differentiate into various neural cells. Co-transplantation of cells/PLGA can promote the functional recovery of the injured spinal cord. The effect of co-transplanting NSC + SCs/PLGA is better than transplanting NSC/PLGA alone.</p>

Fabrication and characteristics of oriental poly (lactic-co-glycolic acid) scaffold: a preliminary study / 中华外科杂志

<p><b>OBJECTIVE</b>To explore the method of fabricating oriental scaffolds and investigate the biocompatibility of the scaffolds as well as cells distribution within the scaffolds in vitro.</p><p><b>METHODS</b>The oriental poly (lactic-co-glycolic acid) (PLGA) scaffolds were fabricated with modified emulsion-phase separation method. The scaffolds were treated with plasma and then anchored with collagen I. Articular chondrocytes were loaded into the scaffolds. The growth status and distributing characteristic of the cells were investigated by environmental scanning electron microscope.</p><p><b>RESULTS</b>The scaffold was well compatible with the articular chondrocytes. The cells could reach to 2.5 mm depth with unilateral loading. The cells distributed evenly in the scaffold and lined along the inner pipes.</p><p><b>CONCLUSIONS</b>The oriental scaffold fabricated could significantly promote the distributing characteristics of the chondrocytes. The vertical alignment of the chondrocytes within the scaffold is closely similar to that of articular cartilage.</p>

Research about schwann cells and PLGA implanted to rat transected spinal cord / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the recovery of rat transected spinal cord injury after implantation of Schwann cells combined with poly (lactide-co-glycolide) (PLGA).</p><p><b>METHODS</b>Schwann cells were expanded, co-cultured with PLGA for 9 days in vitro, and then analyzed with scanning electron microscope (SEM). Rat spinal cord at the level of T(9) was transected. Schwann cells labeled with BrdU and PLGA scaffold were implanted to injury site. After 1, 3, 6 months, BrdU/MBP immunohistochemistry double staining, semi-thin sections stained thionin and ultra-thin section were performed to investigate myelin renew. BBB open field locomotion, motor evoked potential (MEP), compound muscle action potential (CMAP) and somatosensory evoked potential (SEP) were recorded.</p><p><b>RESULTS</b>Schwann cells grew well on PLGA under SEM. BrdU/MBP double positive cells would been seen, remyelination was thin and formed by Schwann cells at 6 months later under electron microscope (EM). BBB behavioral tests revealed no significant difference in recovery comparing with experiment group and control group. The results of MEP, CMAP and SEP showed no significant improvement in the conduction of spinal cord.</p><p><b>CONCLUSIONS</b>There are the compatibility between Schwann cells and PLGA. Although remyelination was found in morphology, function conduction of spinal cord failed to be established.</p>

Human vascular smooth muscle cells and endothelial cells cocultured on polyglycolic acid (70/30) scaffold in tissue engineered vascular graft / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Current prosthetic, small diameter vascular grafts showing poor long term patency rates have led to the pursuit of other biological materials. Biomaterials that successfully integrate into surrounding tissue should match not only the mechanical properties of tissues, but also topography. Polyglycolic acid (70/30) has been used as synthetic grafts to determine whether human vascular smooth muscle cells and endothelial cells attach, survive and secrete endothelin and 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha).</p><p><b>METHODS</b>Endothelial cells and smooth muscle cells were isolated from adult human great saphenous vein. They were seeded on polyglycolic acid scaffold in vitro separately to grow vascular patch (Groups A and B respectively) and cocultured in vitro to grow into vascular patch (Group C). Smooth muscle cells and endothelial cells were identified by immunohistochemical analysis and growth of cells on polyglycolic acid was investigated using scanning electron microscopy. The levels of endothelin and 6-keto-PGF1alpha in the culturing solutions were examined by radioimmunology to measure endothelial function.</p><p><b>RESULTS</b>Seed smooth muscle cells adhered to polyglycolic acid scaffold and over 28 days grew in the interstices to form a uniform cell distribution throughout the scaffold. Then seed endothelial cells formed a complete endothelial layer on the smooth muscle cells. The levels of endothelin and 6-keto-prostaglandin F1 alpha in the culturing solution were (234 +/- 29) pg/ml and (428 +/- 98) pg/ml respectively in Group C and (196 +/- 30) pg/ml and (346 +/- 120) pg/ml in Group B; both significantly higher than in Groups A and D (blank control group, all P < 0.05).</p><p><b>CONCLUSIONS</b>Cells could be grown successfully on polyglycolic acid and retain functions of secretion. Our next step is to use human saphenous vein smooth muscle cells and endothelial cells to grow tubular vascular grafts in vitro.</p>