The effect of co-transplantation of nerve fibroblasts and Schwann cells on peripheral nerve repair.

Combinations of fibroblasts (Fbs) and corresponding epithelial cells have been widely used in many tissues, such as the skin and breast tissues, to augment tissue repair and remodeling. Recently, a large amount of new data has indicated that nerve Fbs play critical roles in Schwann cells (SCs) and axons in vitro. However, little is known regarding the effects of co-transplanting nerve Fbs and SCs on peripheral nerve repair in vivo. The aim of this study was to investigate the effect of co-transplanting sciatic nerve Fbs (SN-Fbs) and sciatic nerve SCs (SN-SCs) on nerve regeneration. We developed a 5 mm nerve-defect model in mice using a polyurethane (PUR) catheter and then injected one of four different mixtures of cells into the catheters to form the following four groups: pure Matrigel (Control group), SN-Fbs alone (SN-Fb group), SN-Fbs combined with SN-SCs at a ratio of 1:2 (Fb&SC group) and SN-SCs alone (SN-SC group). Histological and functional analyses were performed 3 months later. The results indicated that in vitro, the expression levels of NGF, BDNF and GDNF were significantly higher, and in vivo, a more moderate amount of extracellular matrix was produced in the Fb&SC group than in the SN-SC group. Compared to the other groups, co-transplanting SN-Fbs with SCs at a 1:2 ratio had significantly positive effects on nerve regeneration and functional recovery.

A novel method for obtaining highly enriched Schwann cell populations from mature monkey nerves based on in vitro pre­degeneration.

Schwann cells (SCs) are indispensable for cell therapy and tissue engineering of the peripheral nervous system. Easy access to activated, highly proliferative SCs is necessary for clinical applications. The present study developed a fast, efficient method for obtaining highly purified SCs from the peripheral nerve of a mature Rhesus monkey. The common peroneal nerves of 4­year­old Rhesus monkeys were harvested and subjected to in vitro pre­degeneration in a modified SC culture medium (SCCM). The nerve pieces were subsequently treated enzymatically to dissociate the cells and then cultured for 2 days in SCCM. Cultured cells were treated with purification medium containing Ara­C to assist in restricting the overgrowth of fibroblast­like cells, for 24 h. After another 24­h cultivation period, the cells were subsequently treated with a multiplex collagenase, which enabled SC detachment over fibroblast detachment, and thereby facilitated SC isolation. Finally, SCs were cultured in SCCM. The cell yield was determined by cell counting following enzyme digestion and SC purity was determined from the percentage of SCs with respect to the total number of cells. Following purification, 96.3±3.9% of cells were identified as SCs. In vitro pre­degeneration in the presence of basic­fibroblast growth factor, heregulin ß1 and forskolin maximized the purity and yield of SCs that could be obtained from monkey peroneal nerves. The present study identified a novel technique that can efficiently isolate and purify SCs from mature monkey nerves based on in vitro pre­degeneration.

Fat tissue, a potential Schwann cell reservoir: isolation and identification of adipose-derived Schwann cells.

Schwann cells can be used to promote peripheral nerve repair. However, it is challenging to obtain abundant autologous Schwann cells without sacrificing nerve integrity. In this study, we isolated Schwann cells from murine inguinal adipose tissue and identified the cell phenotype and function in vivo and in vitro. Through H&E and immunofluorescence staining, we detected tiny nerve fibers and Schwann cells in adipose tissue. We evaluated the phenotype of spindle-shaped cells (Schwann cell-like cells, SCLCs) isolated from adipose tissue using immunofluorescence staining and real-time RT-PCR. The results showed that SCLCs expressed specific Schwann cell markers. Analysis of conditioned SCLC culture media showed that, similar to Schwann cells isolated from sciatic nerves, SCLCs secreted NGF and BDNF. SCLCs were harvested from CAG-EGFP transgenic mice and combined with silicone nerve conduits to repair sciatic nerve defects in wild-type mice. Six months post-surgery, we found EGFP-positive SCLCs forming myelin sheaths in the same way as sciatic nerve-derived Schwann cells. This research indicates the existence of Schwann cells in adipose tissue and identifies the spindle-shaped cells isolated from adipose tissue as Schwann cells using in vitro and in vivo evaluations. Thus, SCLCs might be promising seed cells for peripheral nerve tissue engineering.

Human eyelid adipose tissue-derived Schwann cells promote regeneration of a transected sciatic nerve.

Schwann cells (SCs) can promote the regeneration of injured peripheral nerves while the clinical application is limited by donor site complications and the inability to generate an ample amount of cells. In this study, we have isolated human eyelid adipose-derived Schwann cells (hE-SCs) from human eyelid adipose tissue and identified the cell phenotype and function. Using immunofluorescence and H &E staining, we detected subtle nerve fibers and SCs in human eyelid adipose tissue. Immunofluorescence staining indicated that hE-SCs expressed glial markers, such as S100, p75NTR GFAP, Sox10 and Krox20. To explore whether hE-SCs promote the regeneration of injured peripheral nerves in vivo, a Balb/c-nu mice model was used in the study, and mice were randomly assigned to five groups: Matrigel; hE-SCs/P0; hE-SCs/P2; hE-FLCs/P2; and Autograft. After 12 weeks, functional and histological assessments of the regenerated nerves showed that sciatic nerve defect was more effectively repaired in the hE-SCs/P2 group which achieved 66.1 ± 6.5% purity, than the other three groups and recovered to similar level to the Autograft group. These results indicated that hE-SCs can promote the regeneration of injured peripheral nerve and the abundant, easily accessible supply of adipose tissue might be a promising source of SCs for peripheral nerve repair.

Specific marker expression and cell state of Schwann cells during culture in vitro.

Schwann cells (SCs) in animals exist in different developmental stages or wound repair phases, distinguished mainly by the expression of SC-specific markers. No study has yet determined SC state under in vitro culture conditions, and the specific markers expressed in SC are obscure as well. In this study, we harvested sciatic nerves from newborn mice and isolated SCs by an enzyme-digestion method, then we examined the expression profiles of ten markers (S100, p75NTR, Sox10, Sox2, GAP43, NCAM, Krox20, Oct6, MBP, and MPZ) at both the RNA and protein levels in in vitro mouse SCs and speculated their relation with in vivo SC stages. We assayed RNA and protein levels of SC specific markers by immunofluorescence, Western Blot, and real-time quantitative RT-PCR. The results show that the expression of most markers (S100, p75NTR, GAP43, NCAM, Krox20, Oct6, MBP and MPZ) was not detectable in all of early stage cultured SCs. The expression of transcription factors Sox10 and Sox2 was, however, detectable in all SCs. After 8 days, the positive expression rate of all markers except GAP43 and Oct6 was almost 100%.These results indicates Sox10 is a necessary marker for SC identification, while S100 is not reliable. SCs cultured in vitro express Sox2, P75NTR, NCAM, GAP43, Oct6, and MPZ, suggesting that they are similar to in vivo undifferentiated iSCs or dedifferentiated iSCs after nerve injury.

Aesthetic and functional results from nailfold recession following fingertip amputations.

PURPOSE: To analyze the aesthetic and functional results of a technique for nail salvage by recessing the nailfold to increase the exposed nail matrix after fingertip amputation. METHODS: Thirty cases of fingertip amputation with distal partial nail bed defects underwent nailfold recession and pulp reconstruction. We increased nail bed exposure by recessing a rectangle flap of eponychium and reconstructed the pulp with different local flaps depending on the injury geometry. A 0.3- to 0.4-cm-wide rectangular strip of eponychium was de-epithelialized. The eponychial flap was separated from the nail matrix and slid proximally to expose more nail matrix, thereby effectively lengthening the exposed nail bed. RESULTS: The flaps survived in all patients. The exposed nail beds were lengthened 0.3 to 0.4 cm and enlarged 38% to 100%. The fingertips had smooth and natural nail plates with inconspicuous scars on both the eponychium and pulp and no deformities. The sensation and mobility of injured and uninjured contralateral fingers did not differ statistically. All patients were satisfied with the appearance and function of the reconstructed fingertips. CONCLUSIONS: Nailfold recession combined with different local flaps provided for the aesthetic and functional restoration of the fingertip after amputation with partial nail bed defect.

Extended reverse dorsal metacarpal artery flap for coverage of finger defects distal to the proximal interphalangeal joint.

UNLABELLED: Finger reconstruction distal to the proximal interphalangeal (PIP) joint is a challenging task for hand surgeons. Although extended reverse dorsal metacarpal artery (RDMA) flaps were described for coverage of finger defects, reports on repairs beyond the PIP joint are limited. The occurrence of venous congestion of the flaps and their treatments require further clarification. METHODS: Extended RDMA flaps were used to cover the finger defects extending from the PIP joints to the fingertips in a series of 16 patients. The reconstructed fingers included the index, middle, ring, and little fingers; thumb reconstruction was not included in this study. The flap size ranged from 2.5×1.8 to 5×3 cm. A composite flap with a segment of tendon was applied for a complex reconstruction in 4 cases. Either superficial branch of radial nerve or dorsal branch of ulnar nerve was included in flap elevation because of its perineural vascular network contributing to the flap perfusion. The pivot point was located at the level of the middle point of the proximal phalanx, where the communicating branches between the proper palmar digital artery and the dorsal metacarpal artery exist. A teardrop skin pedicle was used to reduce the tension of the flap pedicle. RESULTS: All flaps totally survived except that 1 flap had epidermal loss later salvaged by secondary skin grafting. Venous congestion occurred in the distal part of 5 flaps and was effectively relieved after multiple subcutaneous heparin injections. Neither of the 2 cases of nerve repair resulted in significant improvement in sensation. All donor sites were primarily closed. CONCLUSIONS: Extended RDMA flaps can be effectively applied in the reconstruction of finger defects beyond PIP joint. Its advantages include a simple dissection, single-stage reconstruction, and preservation of digital artery and nerve. The donor site can be primarily closed if the flap width is less than 3 cm. Multiple subcutaneous heparin injection is a preferred solution in cases where venous congestion occurs in the flap.

Facile fabrication of dextran-based fluorescent nanogels as potential glucose sensors.

Glucose-responsive nanogels based on dextran and poly(3-acrylamidophenylboronic acid) (PAAPBA) were fabricated by a facile self-assembly assisted (SAA) strategy. Further introduction of the fluorescent agent 2-[4-(3-hydroxy-4-oxo-4H-chromen-2-yl)phenoxy]ethylacrylamide (3HF-AM) allowed visualization of this glucose sensitivity, thus ensuring their potential use as glucose sensors.

Magnetic resonance imaging monitoring dual-labeled stem cells for treatment of mouse nerve injury.

BACKGROUND AIMS: Adipose-derived stem cells (ADSCs) have shown great promise in the regenerative repair of injured peripheral nerves. Magnetic resonance imaging (MRI) has provided attractive advantages in tracking superparamagnetic iron oxide nanoparticle (SPION)-labeled cells and evaluating their fate after cell transplantation. This study investigated the feasibility of the use of MRI to noninvasively track ADSCs repair of peripheral nerve injury in vivo. METHODS: Green fluorescent protein (GFP)-expressing ADSCs were isolated, expanded, differentiated into an SC-like phenotype (GFP-dADSCs) at early passages and subsequently labeled with SPIONs. The morphological and functional properties of the GFP-dADSCs were assessed through the use of immunohistochemistry. The intracellular stability, proliferation and viability of the labeled cells were evaluated in vitro. Through the use of a microsurgical procedure, the labeled cells were then seeded into sciatic nerve conduits in C57/BL6 mice to repair a 1-cm sciatic nerve gap. A clinical 3-T MRI was performed to investigate the GFP-dADSCs in vitro and the transplanted GFP-dADSCs inside the sciatic nerve conduits in vivo. RESULTS: The GFP-dADSCs were efficiently labeled with SPIONs, without affecting their viability and proliferation. The labeled cells implanted into the mice sciatic nerve conduit exhibited a significant increase in axonal regeneration compared with the empty conduit and could be detected by MRI. Fluorescent microscopic examination, histological analysis and immunohistochemistry confirmed the axon regeneration and MRI results. CONCLUSIONS: These data will elucidate the neuroplasticity of ADSCs and provide a new protocol for in vivo tracking of stem cells that are seeded to repair injured peripheral nerves.

Peripheral nerve repair with epimysium conduit.

Autologous tissues such as skeletal muscle have high biocampatibility and can effectively promote nerve regeneration compared to other biological and artificial materials; however, the reasonable and effective application of skeletal muscle requires further study. The purpose of this investigation was to assess the possibility of preparing a hollow nerve conduit, termed the epimysium conduit (EMC), using thin crimps of epimysium with skeletal muscle fibers and evaluate its effectiveness in repairing peripheral nerve defects. We prepared nerve conduits containing lumen with the external oblique muscle of the CAG-EFGP transgenic mice using microsurgical techniques for bridge repair of a 5-mm long sciatic nerve defect in wild-type mice. Systematic histological and functional assessments of the regenerated nerves were performed 8 and 12 weeks after surgery. EMC was found to effectively repair the sciatic nerve defect with significantly greater effectiveness than artificial conduits; however, the repair effect of EMC was lower than that of autologous nerve grafting for some parameters. In addition, our findings showed that some EMC-derived cell components migrated into the region of the regenerated nerves and contributed to reconstruction. Based on these findings, we conclude that a hollow conduit prepared with epimysium and a few skeletal muscle fibers is ideal for repairing peripheral nerve defects, and the cell components in the grafts contribute to nerve regeneration and structural remodeling, which provides an alternative option for the emergency primary repair of peripheral nerve defects in clinical practice.

MRI of iron oxide nanoparticle-labeled ADSCs in a model of hindlimb ischemia.

Adipose-derived stem cells (ADSCs) exhibit tremendous potential for repair of ischemic diseases. However, studies on the fate, migration, differentiation, and body distribution of the labeled ADSCs are rarely reported. In this study, magnetic iron oxide nanoparticles were designed, synthesized, and coated with meso-2,3-dimercaptosuccinic acid (DMSA) to produce DMSA nanoparticles (DMSA-NPs). The properties, size distribution, and characterization of DMSA-NPs were evaluated. Green fluorescent protein expressing ADSCs (GFP-ADSCs) were obtained and labeled with DMSA-NPs. The viability, cytotoxicity and multi-differentiation capacity of labeled GFP-ADSCs were evaluated in vitro. Labeled and non-labeled GFP-ADSCs were injected into a mouse model of hindlimb ischemia, and 3T magnetic resonance imaging (MRI) was acquired. The synthesized DMSA-NPs efficiently labeled the GFP-ADSCs in vitro and in vivo without affecting cell viability, proliferation, cell cycle, and multi-differentiation capacity. The MRI showed hypointense spots in the labeled GFP-ADSCs that lasted up to 8 weeks. Prussian blue staining and immunofluorescence assay at 4 and 8 weeks indicated that the labeled GFP-ADSCs were in and around the ischemic sites and some differentiated into capillaries. This observation is identical to that seen for transplants of unlabeled cells. Labeled cells were also identified mainly in the liver and spleen, with significantly smaller amounts in the lungs, intestines, heart, and kidney. Developed DMSA-NPs were shown to exhibit a considerable potential for use as nanoprobes for MRI of stem cells, which will enhance our understanding of cell-based therapeutic strategies for ischemic diseases.

Novel method for culturing Schwann cells from adult mouse sciatic nerve in vitro.

Schwann cells (SCs) are important in the recovery of peripheral nerve injury and are valuable cells for the tissue engineering of artificial neurons. Clinical applications that require pure SCs in large quantities are limited since human and mouse SCs do not attach well to the wall of the culture dish and have low proliferative potential. To obtain high quantities of highly pure SCs, we developed a new method for culturing SCs from the mouse sciatic nerve in vitro. Approximately 1.5 cm of the bilateral sciatic nerve of a c57 adult mouse was surgically removed and pre-cultured in DMEM containing either 10% FBS or growth factors. One week later, the in vitro SC culture was observed using light microscopy following enzyme digestion. Cell numbers and cell attachment were examined. The purity of the SCs was determined using s100ß and p75NTR staining. Sciatic nerves that had not been pre-cultured were used as the control group. When the excised tissue was pre-cultured in vitro, high yields of SCs were obtained. The SCs were more likely to adhere and the purity was approximately 98% at the p1 generation following simple purification steps, which was significantly higher than the purity obtained from the control group. The pre-culturing of the sciatic nerve prior to in vitro tissue culturing significantly increased the quantity and quality of the SCs.

Dispase rapidly and effectively purifies Schwann cells from newborn mice and adult rats.

In the present study, Schwann cells were isolated from the sciatic nerve of neonatal mice and purified using dispase and collagenase. Results showed that after the first round of purification with dispase, most of the Schwann cells appeared round in shape and floated in culture solution after 15 minutes. In addition, cell yield and cell purity were higher when compared to the collagenase group. After the second round of purification, the final cell yield for the dispase group was higher than that for the collagenase group, but no significant difference was found in cell purity. Moreover, similar results in cell quantity and purity were observed in adult Sprague-Dawley rats. These findings indicate that purification with dispase can result in the rapid isolation of Schwann cells with a high yield and purity.

Ciliary neurotrophic factor-coated polylactic-polyglycolic acid chitosan nerve conduit promotes peripheral nerve regeneration in canine tibial nerve defect repair.

A variety of nerve conduits incorporated with chemical and biological factors have been developed to further stimulate nerve regeneration. Although most of the nerve guides in studies are basically limited to bridge a short gap of nerve defect in rat models, it is vital to evaluate effects of conduits on nerve regeneration over distance greater than 20 mm, or more clinically relevant nerve gap lengths in higher mammals. In this study, a poly(lactide-co-glycolide) (PLGA) nerve conduit, treated with pulsed plasma and coated with ciliary neurotrophic factor (CNTF) as well as chitosan, was used to repair 25-mm-long canine tibial nerve defects in eighteen cross-bred dogs. The canines were randomly divided into three groups (n = 6), a 25-mm segment of the tibial nerve was removed and replaced by a PLGA/chitosan-CNTF nerve conduit, PLGA/chitosan conduit and autologous nerve grafts were performed as the control. The results were evaluated by general observation, electromyogram testing, S-100 histological immunostaining, and image analysis at 3 months after operation. The histological results demonstrated that the PLGA/chitosan-CNTF conduits and PLGA/chitosan conduits were capable of leading the damaged axons through the lesioned area. Through the comparison of the three groups, the results in PLGA/chitosan-CNTF conduits group were better than that of PLGA/chitosan conduits group, while they were similar to autologous nerve grafts group. Therefore, CNTF-coated PLGA/chitosan nerve conduits could be an alternative artificial nerve conduit for nerve regeneration.

[Clinical effect of distally-based dorsal thumb neurocutaneous vascular flap on repair of soft tissue defect in thumb].

OBJECTIVE: To investigate the surgical methods and clinical results of repairing soft tissue defects in the thumb with distally-based dorsal thumb neurocutaneous vascular flap. METHODS: From January 2006 to October 2007, 23 patients with soft tissue defect in the thumb were treated, including 20 males and 3 females aged 19-46 years old (average 27.5 years old). The defect was caused by crush injury in 1 case, electric planer accident in 6 cases, incised injury in 8 cases, and avulsion injury in 8 cases. The defect was located on the palmar aspect of the thumb distal phalanx in 3 cases, the dorsal-radial aspect of the thumb distal phalanx in 3 cases, and ulnar or dorsal aspect in 17 cases. The defect size ranged from 3.3 cm x 1.2 cm to 4.2 cm x 1.2 cm. Among them, 18 cases were complicated with distal 1/2 nail bed defect or injury. The time between injury and hospital admission was 1-72 hours (average 22 hours). During operation, the defect was repaired with distally-based dorsal-radial neurovenocutaneous vascular flap of the thumb in 3 cases and distally-based dorsal-ulnar neurovenocutaneous vascular flap of the thumb in 20 cases. The size of those flaps was 4.0 cm x 1.6 cm-5.0 cm x 3.0 cm. The donor site underwent direct suture or split thickness skin graft repair. RESULTS: At 10 days after operation, 3 cases suffered from the epidermal necrosis in the distal part of the flap, 2 of them experienced the exfoliation of dark scab 14 days later and the flap survived, and the flap of the rest one survived after dressing change. The other flaps and the skin graft at the donor site all survived uneventfully. The wounds healed by first intention. All the patients were followed up for 10-16 months (average 12.6 months). The flaps were soft in texture and full in appearance. The two-point discrimination value 6 months after operation was 8-10 mm. At 12 months after operation, the growth of the residual fingernail was evident in 18 cases, including 4 cases of curved or hook fingernail. Active flexion and extension of the thumb were normal. The abduction of the first web space reached or surpassed 80 percent of the normal side in 20 cases and was below 80 percent of the normal side in 3 cases. The clinical outcomes were satisfactory in 11 cases, approximately satisfactory in 8 cases, and unsatisfactory in 4 cases according to self-designed evaluation system. CONCLUSION: The operative method of repairing the soft tissue defects in the thumb with the distally-based dorsal thumb neurocutaneous vascular flap is simple, stable in anatomy, in line with the principle of proximity, and suitable for repairing thumb tip defect 3 cm in size. It can bring a good postoperative appearance of the thumb and little influence on the hand function.

[Tissue engineered nerve based on plasma treatment and BMSCs].

OBJECTIVE: To evaluate the effect of the plasma treated PLGA nerve conduits seeded BMSCs on repairing SD rat sciatic nerve defects. METHODS: BMSCs were acquired from 30 newborn SD rats. After amplified and passaged for 3 times, PLGA nerve conduits were prepared and some of them were treated with plasma. A 1-cm-length sciatic nerve defect was made in 30 4-week-old SD rats, then they were randomly divided into 3 groups for three different nerve defects reconstruction methods (n = 10). In the experimental group, defect was repaired by plasma treatment and PGLA nerve conduits seeded with BMSCs; in the control group, by normal PLGA nerve conduits seeded with BMSCs; and in the autologous group, by autologous nerve. At 6 weeks after the surgery, the dynamic walking pattern was recorded and the sciatic function index (SFI) was calculated; the electrophysiological test was taken; the gastrocnemius wet weight recovery rate was calculated; and the image analysis of regenerated nerve was made. RESULTS: All rats survived after the surgery and lived to the end of the experiment. At 6 weeks after the surgery, the dynamic walking pattern of the experimental group and autologous group was better than that of the control group. The SFI value of the experimental, control and autologous groups was -51.02 +/- 6.54, -58.73 +/- 7.87 and 48.73 +/- 3.95, respectively, showing statistically significant differences among the experimental group, control group and autologous group (P < 0.05). The results of the motor nerve conduction velocity and wave amplitude showed that there were statistically significant differences between the experimental group and the control group (P < 0.05), and between the control group and the autologous group (P < 0.01); but no significant difference between the experimental group and autologous group (P > 0.05); The gastrocnemius wet weight recovery rate of the experimental, control and autologous groups was 56.13% +/- 4.27%, 43.14% +/- 6.52%, 59.47% +/- 3.85%, respectively; showing statistically significant differences among experimental group, control group and autologous group (P < 0.05). The density, diameter of regenerated nerve fiber as well as neural sheath thickness of the experimental group were all higher than those of the control group (P < 0.05) and lower than those of the autologous nerve group (P < 0.05); there was significant difference between the control group and the autologous group (P < 0.01). CONCLUSION: Plasma treated PLGA nerve conduits seeded with BMSCs can effectively repair sciatic nerve defects and provide a new strategy for the development of tissue engineered nerve to repair the peripheral nerve defects.

[Reconstruction of bone using tissue engineering and nanoscale technology].

OBJECTIVE: To explore the method of fabricating freeze-dried demineralized bone matrix with nanoscale topography (nFDBM) and to investigate the feasibility of reconstruction of tissue-engineered bone with the novel scaffold. METHODS: Allogenic dogs' phalangeal cortical bone was fabricated into freeze-dried demineralized bone (FDBM) with modified Urist's method. FDBM was subjected to Nd : YAG laser irradiation under special conditions. The surface topography was identified by atomic force microscope (AFM) and scanning electron microscope (SEM). The osteoblasts were induced from autologous mesenchymal stem cells (MSCs) and mixed with nFDBM and FDBM in vitro. The effects of the different topography on cell-behavior was identified by SEM. The complex of nFDBM and osteoblasts were implanted into fascial bags on dogs' back (experimental group A) and dogs' phalangeal defects on right (experimental group C), while FDBM-osteoblast complex (control group B) and unique FDBM (control group D) were implanted into the corresponding sites on left as control groups. The osteogenic status was assessed by X-ray, HE and SEM at 4, 8 and 12 weeks after surgery. RESULTS: The surface of FDBM subjected to Nd : YAG laser irradiation resulted in well-defined three-dimensional nanoscale grooves (150 nm in depth and 600 to 800 nm in width). When the osteoblasts were implanted on the scaffold, the cells adhering to nFDBM were more than those to FDBM and secreted more extracellular matrix. Either new bone-like thin layer on the nanoscale surface or a lot of new bone-formation inner the experimental complex was observed by HE after 12 weeks of surgery and the experimental complexes were partially calcified at the same time, while the control groups almost had no osteogenic phenomena. CONCLUSION: Nd : YAG laser could produce nanoscale grooves on the FDBM surface. The nanoscale grooves are conductive to adherence, proliferation and matrix secretion of osteoblasts. Complexes by tissue engineering and nanoscale technology have some osteogenic abilities in vivo after implanted the animal model.

[An experimental study on transplantation of frozen canine phalangeal joint allografts incorporated with autogenic bone marrow].

OBJECTIVE: To investigate the result of the transplantation of frozen canine phalangeal joint allografts perforated and incorporated with autogenic bone marrow. METHODS: A proximal interphalangeal joint defect of 1.5 cm was prepared at bilateral sides of twenty-four adult healthy out-bred dogs. Three different types of allografts were applied to repair the defects: fresh autogenic phalangeal joints (group A, n = 16), frozen phalangeal joint allografts perforated and incorporated with fresh autogenic bone marrow (group B, n = 16), and frozen phalangeal joint allografts (group C, n = 16). Radiographic and histological study were used to evaluate the survival of transplanted joints. The observation was done 1, 3, 6 and 12 months after operation respectively. RESULTS: Based on the radiographic and histological changes of the transplanted joints, the osteoarthropathy of transplanted canine phalangeal joints could be divided into 3 degrees: mild degeneration, moderate degeneration and severe degeneration. Mild degeneration was observed in group A from 3 to 12 months. Mild degeneration was also found in group B from 1 to 6 months, and the endochondral ossification was obvious within the drilled bony holes. However, some joints in group B underwent moderate degeneration 12 months after operation. Group C joints in the first month had moderate degeneration, which progressed to severe degeneration 3 months after operation. CONCLUSION: Transplantation of frozen canine phalangeal joint allografts perforated and incorporated with autogenic bone marrow can effectively delay the degeneration of transplanted osteoarticular allografts at the early and middle stage.

[Experimental study on nerve conduit coated with chitin and filled with a guide-fiber].

OBJECTIVE: To study the result of using nerve conduit coated with chitin and filled with a guide-fiber to repair peripheral nerve defect. METHODS: Twenty-four female adult SD rats were made the model of 14 mm-gap on bilateral sciatic nerve under sterile condition. The rats were randomly divided into 4 groups (n=6), group A: polymer polyglycolic-lactic acid (PGLA) nerve conduit coated with chitin and filled with a guide-fiber as experimental group to repair 14 mm-gap of rat sciatic nerve;group B: PGLA nerve conduit coated with chitin; group C: PGLA nerve conduit; group D: autograft (control group). The repair result was evaluated by normal observation, EMG testing and S-100 histological immunostaining analysis 4 and 12 weeks after operation. RESULTS: Four weeks after the operation, there were new regenerated immature fibers in groups A, B and C, 12 weeks after the operation, the regenerated nerve fibers were seen to have bridged the gap. There were myelinated fibers equably distributed and rarely new generated nerve fibers in distal parts of group D. The repair result of PGLA nerve conduit coated with a chitin and filled with guide-fiber was better than that of groups B and C (P<0. 05). There was significant difference of nerve fiber diameter, thickness of myelin sheath and fiber density in group D from those in groups A, B and C (P<0. 05), but there were degenerative changes such as vacuoles in sheaths and myelin separation in proximal and few new regenerated nerve fibers in distal parts of group D. CONCLUSION: PGLA nerve conduit coated with chitin and filled with a guide-fiber offers a possible substitute for the repair of peripheral nerve defect.