Objective To prepare a self-made compound, hemostatic jelly with polylactic acid(PLA), which has the hemostatic and absorbable effect on injured cancellous bone. Methods Two bone defects of 5 mm in diameter and 4 mm in depth were subjected on 20 health rabbits by drilling through their either outside plate of the iliac, and were filled with hemostatic jelly(group A), bone wax(group B) and blank(group C) respectively. Hemostasis were observed and recorded after 1 and 10 minutes. Five specimens were harvested at 2, 4, 8 and 12 weeks postoperatively for histological observation. Results ① Hemostatic effect: Bleeding of injured spongy bone stopped within 10 minutes after the treatment of hemostatic jelly and bone wax, but bleeding of balnk did not stop. Hemostatic jelly and bone wax adhered to bone defects firmly within 10 minutes was after the treatment. ② Absorbable effect: Hemostatic jelly and bone defects have not changed visibly in the first 2 weeks. With histological observation 4 to 8 weeks after the operation, hemastatic jelly was absorbed gradually and replaced by osteogenous tissue. It was absorbed completely after 8 to 12 weeks. Bone wax was not absorbed after 12 weeks, no new bone tissue was observed at bone wax area. The blank was replaced by connective tissue and osteogenous tissue partially after 12 weeks. Conclusion The compound hemostatic jelly manifests both hemostatic and absorbable effects on injured cancellous bone and may substitute for bone wax in clinical application.
Objective To study the mechanism of ectopic osteogenesis of nacre/Polylactic acid (N/P) artificial bone combined with allogenic osteoblasts, and to explore the possibility as a scaffold material of bone tissue engineering. Methods The allogenic- osteoblasts seeded onto N/P artificial bone were co-cultured in vivo 1 week.The N/P artificial bone with allogenic osteoblasts were implanted subcutaneously into the left back sites of the New Zealand white rabbits in the experimental group and the simple N/P artificial bone into the right ones in the control group. The complexes were harvested and examined by gross observation, histologic analysis and immunohistochemical investigation 2, 4 and 8 weeks after implantation respectively.Results In experimental group, the osteoid formed after 4 weeks, and the mature bone tissue withbone medullary cavities formed after 8 weeks; but in control group there was nonew bone formation instead of abundant fibrous tissue after 4 weeks, and more fibrous tissue after 8 weeks.Conclusion N/P artificial bone can be used as an optical scaffold material of bone tissue engineering.
Objective To investigate the clinical effect of polylactic acid membrane in prevention of epidural scar and adhesion. Methods From July 1998 to April 2000, 62 patients with lumbar disc herniation were randomly assigned into two groups. All were treated surgically with discectomy by fenestration or laminectomy.One group were placed with a thin of polylactic acid membrane covering the interlaminar space(n=32). The thickness of the film was 0.1mm. The other group was blank control(n=30). After 2 weeks of operation, we observed the local and systemic reactions. After 6 months clinical symptoms were revaluated and the degrees of epidural scar and adhesion were determined by CT scans. Results After 2 weeks, we found no adverse systemic reactions in all patients. Wound healing was excellent. No abnormalities of hepatic and renal functions as well as blood for routine were found. Temperature after operation was normal. After 6 months, the curative effects were as follows in experimental group and in control group: excellent in 27 patients and in 24 patients, good in 4 patients and in 4 patients, fair in 1 patient and in 1 patient, and poor in 0 patient and in 1 patient, respectively. There are no significant difference between two groups. The CT scans showed no adhesion between the epidural scar and the dural sac in all patients of experimental group. There existed various extents of adhesion in control group. Conclusion The results demonstrate that the polylactic acidmembrane can effectively prevent the epidural scar adhesion with a good biocompatibility and no toxity. Its clinical application was promising.
OBJECTIVE To confirm membrane-guided tissue regeneration in the healing course of segmental bone defects and study the mechanism. METHODS Segmental, 1 cm osteoperiosteal defects were produced in both radii of 12 rabbits. One side was covered with hydroxyapatite/polylactic acid(HA/PLA) membrane encapsulated as a tube. The contralateral side served as an untreated control. Healing courses were detected by radiographic and histologic examinations. RESULTS All control sides showed nonunion, whereas there were consistent healing pattern in test sides. CONCLUSION Membrane technique can promote bone regeneration.
In order to find an ideal biological material to prevent peridural adhesion following laminectomy, 30 rabbits were used as animal model, in each of which 2 defects with a size of 1 cm x 0.5 cm were made following laminectomy of L3, L5 spine. One of the defects was covered extradurally with chitosan, gelatin foam or PLA membrane respectively, while the other defect was exposed as control. All of these animals were sacrificed on the 2nd, 4th, 6th, 8th and 10th week after operation, and the extradural fibrosis and adhesion of every animal were evaluated by gross observation and histological examinations. It was revealed that in the chitosan and PLA membrane groups, the extradural tissue was smooth without thickening and there was no fibrous proliferation or adhesion in the epidural cavity, and that in the chitosan group, the growth of fibroblast was restrained but the growth of the epithelial cells was promoted significantly, thus, wound healing was rapid. In the control group and gelatin foam group, obvious extradural fibrosis and adhesion were observed and the extradural space had almost disappeared. Therefore, it was concluded that the biodegradable PLA membrane and chitosan were both an ideal material in the prevention of postoperative epidural adhesion.
ObjectiveTo investigate the influences of lactic acid (LA), the final degradation product of polylactic acid (PLA) on the prol iferation and osteoblastic phenotype of osteoblast-l ike cells so as to provide theoretical basis for bone tissue engineering. MethodsRos17/2.8 osteoblast-l ike cells were harvested and divided into 3 groups. In groups A and B, the cells were cultured with the medium containing 4, 8, 16, 22, and 27 mmol/L L-LA and D, L-LA, respectively. In group C, the cells were cultured with normal medium (pH7.4). The cell prol iferation was determined with MTT method after 1, 3, and 5 days. The relative growth ratio (RGR) was calculated, and the cytotoxicity was evaluated according to national standard of China. In addition, the alkal ine phosphatase (ALP) activity of cells cultured with medium containing 4 mmol/L L-LA (group A), 4 mmol/ L D, L-LA (group B), and normal medium (group C) after 1 and 5 days were detected with ALP kits, and the relative ALP ratio (RAR) was calculated; after 21 days, the calcium nodules were tested with von Kossa staining method, and were quantitatively analyzed. ResultsWhen LA concentration was 4 mmol/L, the mean RGR of both groups A and B were all above 80%, and the cytotoxic grades were grade 0 or 1, which meant non-cytotoxicity. When LA concentration was 8 mmol/L and 16 mmol/ L, groups A and B showed cytotoxicity after 5 days and 3 days, respectively. When LA concentration was above 22 mmol/L, cell prol iferations of groups A and B were inhibited evidently after 1-day culture. At each LA concentration, RGR of group A was significantly higher than that of group B at the same culture time (P<0.05) except those at 4 mmol/L after 1-day and 3-day culture. After 1 day, the RAR of group A was significantly higher than that of group B on 1 day (144.1%±3.2% vs. 115.2%±9.8%, P<0.05) and on 5 days (129.6%±9.8% vs. 78.2%±6.9%, P<0.05). The results of von Kossa staining showed that the black gobbets in group A were obviously more than those of groups B and C. The staining area of group A (91.2%±8.2%) was significantly higher than that of groups B (50.3%±7.9%) and C (54.2%±8.6%) (P<0.05). ConclusionThe concentration and composition of LA have significant effects on the cell proliferation and osteoblastic phenotype of osteoblast-l ike cells.
ObjectiveTo improve the poor mechanical strength of porous ceramic scaffold, an integrated method based on three-dimensional (3-D) printing technique is developed to incorporate the controlled double-channel porous structure into the polylactic acid/β-tricalcium phosphate (PLA/β-TCP) reinforced composite scaffolds (double-channel composite scaffold) to improve their tissue regeneration capability and the mechanical properties. MethodsThe designed double-channel structure inside the ceramic scaffold consisted of both primary and secondary micropipes, which parallel but un-connected. The set of primary channels was used for cell ingrowth, while the set of secondary channels was used for the PLA perfusion. Integration technology of 3-D printing technique and gel-casting was firstly used to fabricate the double-channel ceramic scaffolds. PLA/β-TCP composite scaffolds were obtained by the polymer gravity perfusion process to pour PLA solution into the double-channel ceramic scaffolds through the secondary channel set. Microscope, porosity, and mechanical experiments for the standard samples were used to evaluate the composite properties. The ceramic scaffold with only the primary channel (single-channel scaffold) was also prepared as a control. ResultsMorphology observation results showed that there was no PLA inside the primary channels of the double-channel composite scaffolds but a dense interface layer between PLA and β-TCP obviously formed on the inner wall of the secondary channels by the PLA penetration during the perfusion process. Finite element simulation found that the compressive strength of the double-channel composite scaffold was less than that of the single-channel scaffold; however, mechanical tests found that the maximum compressive strength of the double-channel composite scaffold[(21.25±1.15) MPa] was higher than that of the single-channel scaffold[(9.76±0.64) MPa]. ConclusionThe double-channel composite scaffolds fabricated by 3-D printing technique have controlled complex micropipes and can significantly enhance mechanical properties, which is a promising strategy to solve the contradiction of strength and high-porosity of the ceramic scaffolds for the bone tissue engineering application.
ObjectiveTo investigate the effect of electrospun chitosan/polylactic acid (ch/PLA) nerve conduit for repairing peripheral nerve defect in rats. MethodsNerve conducts loaded with ch/PLA was made by the way of electrospun. The mechanical property, hydrophility, biocompatibility were tested, and the scanning electron microscope was used to observe the ultrastructure. The same experiments were also performed on pure PLA nerve conducts as a comparison. Then, 54 Sprague Dawley rats were divided into 3 groups randomly, 18 rats in each group. Firstly, the 10 mm defects in the right sciatic nerves were made in the rats and were respectively repaired with ch/PLA (group A), autografts (group B), and no implant (group C). At 4, 8, and 12 weeks after operation, general observations, sciatic functional index (SFI), electrophysiological evaluation, wet weight of gastrocnemius and soleus muscles, histological examination, immunohistological analysis, and transmission electron microscopy were performed to evaluate the effects. ResultsCompared with pure PLA nerve conducts, the addition of chitosan could improve the mechanical property, hydrophility, biocompatibility, and ultrastructure of the nerve conducts. At 4 weeks postoperatively, the regenerated nerve bridged the nerve defect in group A. The SFI improved gradually in both group A and group B, showing no significant difference (P>0.05). Compound muscle action potentials and nerve conduction velocity could be detected in both group A and group B at 8 and 12 weeks after operation, and significant improvements were shown in both groups (P<0.05). The wet weight and myocyte cross section of gastrocnemius and soleus muscles showed no significant difference between group A and group B (P>0.05), but there was significant difference when compared with group C (P<0.05) at 12 weeks postoperatively. Immunohistological analysis revealed that S-100 positive Schwann cells migrated in both group A and group B, and axon also regenerated by immunohistological staining for growth associated protein 43 and neurofilaments 160. Transmission electron microscopy showed no significant difference in the diameter of nerve fiber between group A and group B (P>0.05), but the thickness of myelin sheath in group A was significantly larger than that in group B (P<0.05). ConclusionThe electrospun ch/PLA nerve conduits can effectively promote the peripheral nerve regeneration, and may promise an alternative to nerve autograft for repairing peripheral nerve defect.