Experiment of non-vascularized iliac bone grafts with the simultaneous placement of titanium nnplants

AIM:To investigate the osseointegration process of titanium implant and non-vascularized iliac bone grafts.METHODS:12 mongrel were divided into 4 groups randomly.Bone grafts were resected from iliac crest and then transplanted to the other side.Animals were skilled in different time after surgery,X-ray pictures were taken,then histological observation were done.RESULTS:At 3rd week,bone grafts dissolved,resorbed or necrosis partly;At 6th week,new bone began to regenerated;At 9th week,the amount of new bone increased;At 12nd week,bone interface around implant formed,without soft tissue interrupt.CONCLUSION:Osseointegration can formed between non-vascularized iliac bone grafts and titanium implant.

Correction of mandibular deficiency by inverted-L osteotomy of ramus and iliac crest bone grafting

This study was to describe the use of inverted-L osteotomy of ramus and lilac bone graft for the management of mandibular deficiency in adult patients. From 2008 to 2010, 11 patients （aged 19 to 29 years） with mandibular deficiency underwent intraoral or extraoral inverted-L osteotomy of ramus and lilac crest bone grafting. Data were collected from the patients＇ records, photographs and radiographs. The height and width of the ramus were successfully expanded by inverted-L osteotomy and lilac crest bone grafting with minimal complications in all patients, resulting in significant improvement in occlusion and facial appearance. Our early results showed that the inverted-L osteotomy of ramus and lilac crest bone grafting is safe and effective, and should be considered as a good alternative for the patients with mandibular deficiency.

Treatment of Thoracolumbar Vertebrate Fracture by Transpedicular Morselized Bone Grafting in Vertebrae for Spinal Fusion and Pedicle Screw Fixation

To enhance the fusion of graft bone in thoracolumbar vertebrae and minimize the postoperative loss of correction, short-segment pedicle screw fixation was reinforced with posterior moselizee bone grafting in vertebrae for spinal fusion in patients with thoracrolumbar vertebrate fractures. Seventy patients with thoracrolumbar vertebrate fractures were treated by short-segment pedicle screw fixation and were randomly divided into two groups. Fractures in group A （n=20） were rein-forced with posterior morselized bone grafting in vertebrae for spinal fusion, while patients group B （n=50） did not receive the morselized bone grafting for bone fusion. The two groups were compared in terms of kyphotic deformity, anterior vertebral height, instrument failure and neurological functions after the treatment. Frankel grading system was used for the evaluation of neurological evaluation and Denis scoring scale was employed for pain assessment. The results showed that the kyphosis correction was achieved in both group A and group B （group A： 6.4 degree; group B： 5.4 degree）/At the end of follow-up, kyphosis correction was maintained in group A but lost in group B （P=0.0001）. Postoperatively, greater anterior height was achieved in group A than in group B （P〈0.01）. During follow-up study, anterior vertebral height was maintained only in Group A （P〈0.001）. Both group A and group B showed good Denis pain scores （P1 and P2） but group A outdid group B in terms of control of severe and constant pain （P4 and P5）. By Frankel criteria, the changes in neurological functions in group A was better than those of group B （P〈0.001）. It is concluded that reinforcement of short-segment pedicle fixation with morselized bone grafting for the treatment of patients with thoracolumbar vertebrae fracture could achieve and maintain kyphosis correction, and it may also increase and maintain anterior vertebral height. Morselized bone grafting in vertebrae offers immediate spinal stability in patients with thoracolumbar vertebrate fractures, decreases the instrument failure and provides better postoperative pain control than without the morselized bone grafting.

Acellular allogeneic nerve grafting combined with bone marrow mesenchymal stem cell transplantation for the repair of long-segment sciatic nerve defects:biomechanics and validation of mathematical models

We hypothesized that a chemically extracted acellular allogeneic nerve graft used in combination with bone marrow mesenchymal stem cell transplantation would be an effective treatment for long-segment sciatic nerve defects.To test this,we established rabbit models of 30 mm sciatic nerve defects,and treated them using either an autograft or a chemically decellularized allogeneic nerve graft with or without simultaneous transplantation of bone marrow mesenchymal stem cells.We compared the tensile properties,electrophysiological function and morphology of the damaged nerve in each group.Sciatic nerves repaired by the allogeneic nerve graft combined with stem cell transplantation showed better recovery than those repaired by the acellular allogeneic nerve graft alone,and produced similar results to those observed with the autograft.These findings confirm that a chemically extracted acellular allogeneic nerve graft combined with transplantation of bone marrow mesenchymal stem cells is an effective method of repairing long-segment sciatic nerve defects.

Histological Assessment of Bone Regeneration in the Maxilla with Homologous Bone Graft:A Feasible Option for Maxillary Bone Reconstruction

Bone biomaterials have been increasingly used to reconstruct maxillary atrophic ridges.Thus,the aim of this study was to evaluate bone reconstruction in the maxilla using a homologous cortico-cancellous FFB(lyophilized)graft and verify its reliability.Eight individuals were included from 2014 to 2018.The first surgery was performed to install homologous bone blocks in the maxilla.The period of the second intervention varied between 5 months and 15 days to 11 months(≈7.93 months).The biopsies were taken from the central region of the matured graft during the surgery for implant placement.All patients presented clinical and radiographic conditions for the installation of dental implants.There was a 100%of survival rate.The histological assessment showed that the homologous block bone graft was an osteoconductive biomaterial,with connective tissue present,and newly formed bone juxtaposed on its surface.There were bone trabeculae with osteocytes and active osteoblasts with connective tissue in the mineralization process;the remodeling process can be found through the reverse lines.A limited focus of necrosis with fibrosis was detected,with small resorption and areas of inflammatory infiltrate,but without clinical significance.The homologous block bone graft can be considered a feasible option to substitute the autogenous bone graft(gold standard),with predictable clinical and favorable histological results.The patients had a shorter surgical period,low morbidity,and an unlimited amount of biomaterial available at an accessible cost.

Spoon-assisted autologous particulate bone graft harvesting technique

Particulate bone plays a crucial role in various oral and maxillofacial surgical procedures,including reconstruction,implantation,and craniofacial surgery.Autologous bone and deproteinized bovine bone xenografts are the two primary resources used for such procedures,with the former demonstrating superior cost-effectiveness and reduced comorbidity rates,particularly in cases involving donor zones.However,a significant challenge lies in acquiring uniformly sized autologous particulate bone specimens,with existing tools often yielding coarse particles at a high cost.Consequently,commercial bone xenograft solutions are frequently favored despite lower standards.This technical note introduces a novel technique for swiftly,safely,and efficiently obtaining autologous particulate bone specimens.The procedure involves the use of a motor handpiece fitted with a micro drill and surgical spoon to collect the bone particles.The continuous irrigation with saline maintains a clear surgical field during the milling process.The collected bone particles are then transferred to a metal capsule for further use.This technique offers a promising solution to the challenge of inconsistent particle size associated with harvesting using traditional methods,providing surgeons with a reliable and efficient method of obtaining autologous particulate bone samples.

Epiphyseal distraction and hybrid reconstruction using polymethyl methacrylate construct combined with free non-vascularized fibular graft in pediatric patients with osteosarcoma around knee: A case report

BACKGROUND In children with osteosarcoma around the knee joint without epiphysis involvement,joint-sparing surgery seems to be an ideal way to retain knee joint function.However,there are two points of debate with regard to the technique:How to accurately achieve a safe surgical margin,and how to achieve intercalary reconstruction of the massive bone defect following resection of the tumor.CASE SUMMARY We present the case of an 8-year-old girl with osteosarcoma of the distal femur without involvement of the epiphysis.Epiphyseal distraction was applied to separate the epiphysis and metaphysis,and this provided a safe surgical margin.The massive bone defect was reconstructed with a custom-made antibioticloaded polymethyl methacrylate(PMMA)construct combined with a free nonvascularized fibular graft.Six months after surgery,bone union between the autograft and host bone was confirmed in both the proximal and distal femur by computer tomography(CT)examination.Moreover,considerable callus formation was found around the PMMA construct.After 28 mo of follow-up,there was no sign of recurrence or metastasis.The patient could walk without any aid and carry out her daily life activities satisfactorily.CONCLUSION In cases of osteosarcoma without epiphysis involvement,epiphyseal distraction can be easily applied to obtain a safe margin.Hybrid reconstruction with an antibiotic-loaded PMMA construct combined with a free non-vascularized fibular graft has the advantages of being easy to manufacture,less time-consuming to place,and less likely to get infected,while also ensuring bone union.Our case provides an alternative technique for biological reconstruction after joint-sparing surgery in patients with osteosarcoma around the knee without epiphyseal involvement.

Surgical Treatment of Osteonecrosis of the Femoral Head Using Minimally Invasive Surgical Drilling and Cancellous Grafting at Brazzaville University Hospital

Introduction: Osteonecrosis of the femoral head (ONTF) is a debilitating condition. Several treatments have been proposed with controversial results. The aim of our study was to evaluate treatment by surgical drilling coupled with in situ cancellous grafting. Materials and methods: Our study was a case-control study conducted at Brazzaville University Hospital from 1st January 2018 to 31 December 2023. It compared two groups of patients with ONTF: non-operated (13 patients, 20 hips) and operated (22 patients, 35 hips). We used the visual digital scale (VDS) for pain assessment, the Merle D’Aubigne-Postel (MDP) scoring system for clinical and functional assessment, and the evolution of necrosis. Results: The group of non-operated patients had a mean age of 35.69 ± 3.4 years, no improvement in pain with an EVN above seven at the last recoil and a mean global MDP score falling from 12.7 before offloading to 10.13 at one year. The group of patients operated on had a mean age of 37.86 ± 7.02 years, a significant reduction in pain (p = 0.00004) and a significantly increased MDP score (p = 0.0034). A comparison of the two groups of patients showed significant stabilization of the necrotic lesions in the operated patients (p = 0.00067), with better satisfaction in the same group. Conclusion: Surgical drilling combined with grafting in the treatment of early-stage ONTF has improved progress in our series. The technique is reproducible and less invasive. It has made it possible to delay unfavorable progression and, consequently, hip replacement surgery.

Implementing P-15/ABM Bone Graft as a Standardized Technique for Lumbar Fusion Approaches

Introduction: Lumbar fusion as low back pain treatment continues to be a challenge because of the multiple techniques and materials available, most popular techniques include Transforaminal lumbar interbody fusion (TLIF), Lateral lumbar interbody fusion (LLIF) and Anterior lumbar interbody fusion (ALIF). Successful lumbar fusion is associated with better clinical outcomes, and it is enhanced and targeted through the use of bone graft materials as an osteogenic cell binding peptide P-15, bound to an anorganic bone mineral (ABM). This peptide improves bone formation when used in fixation devices in a targeted and limited way to the implant surface by activating osteoblast precursor cells;by the osteogenic, osteoinductive and osteoconductive stimuli. The main objective of this study is to standardize the lumbar fusion process in the 3 techniques and achieve a more efficient and predictable lumbar fusion, evaluating results with radiological and clinical scales. Material and Methods: Patients underwent lumbar fusion with the use of P-15 Osteogenic Cell Binding Peptide, bound to an anorganic bone mineral (P-15/ABM) bone graft (5 cc) in three different techniques (TLIF, LLIF, ALIF), achieving a total of 100 lumbar levels. Radiological outcomes included fusion rates per Hounsfield Units at computed tomography (CT) scan and Lenke scale. Clinical outcomes were evaluated via the Oswestry Disability Index (ODI), Short Form Performance (SPF-36) and Visual Analog Scale (VAS and VASs) for pain and satisfaction. Results: 67 patients completed the 12 months follow-up, showing no differences in fusion rates between techniques. (Computed Tomography Hounsfield Units) CTHU reaches more than 200 UH at 3 months follow-up and continues fusion process till 12-month follow-up. Clinical scales showed no disability at ODI, improvement at VAS and VASs scales, absence of health restrictions at SPF-36 score since 6 months follow up. Conclusion: Bone graft volume of 5 cc is adequate for achieving successful lumbar fusion, regardless of the surgical technique employed.

Influence of bone morphogenetic protein on articular cartilage regeneration following periosteal grafting

Background: Autologous periosteal grafting is used as treatment for articular cartilage defect. Objective: To study the effect of bone morphogenetic protein (BMP) on articular cartilage regeneration following periosteal grafting. Methods: 16 healthy 15 week-old New Zealand white rabbits of both sexes (32 knees) were randomly divided into experimental group (group A) and control group (group B). A4.0 mmdiameter full-thickness articular cartilage defect was created in the femoral intercondylar fossa in all rabbits. Following this, a4.0 mmdiameter section of the periosteum was harvested from the anteromedial part of the upper tibial bone. In group A (eight rabbits, 16 knees), the cartilage defect was covered with periosteum, into which 20 μg BMP and 20% Pluronic were injected. In group B (eight rabbits, 16 knees), the cartilage defect was covered with periosteum, into which the same dosage of 0.9% NS (Normal saline) and 20% Pluronic were injected. All rabbits were sacrificed at 4, 8, and 12 weeks postoperatively, the cartilage defect areas were examined macroscopically and microscopically, and the morphology of the chondrocytes and collagen fibers were examined by scanning electron microscopy. Results: The filling of the defects with regenerated tissue was observed in both the group. The most notable improvement was that the cartilage regeneration in group A was obviously superior to that in group B, with the total histological score in group A significantly higher. Conclusion: BMP is an effective factor that could promote regeneration of articular cartilage and lead to successful cartilaginous resurfacing following periosteal

Tertiary bone grafting with or without premaxilla osteotomy in adult alveolar clefts—Techniques and early outcome

The outcome of alveolar bone grafting in adult patients is sparsely reported. Here, we present a description of the surgical techniques used in a Nigerian teaching hospital and a preliminary report of the first five cases of adult alveolar cleft bone grafting accomplished with or without repositioning the premaxilla. Although, evidence of bone resorption was observed within 6 months after the operation, satisfactory bone level and aesthetic outcome was recorded in all cases. We concluded that tertiary alveolar bone grafting is desirable for all cases where alveolar clefts have persisted into adulthood to enhance the psyche of the cleft patients and to motivate them for further rehabilitation. Prompt placement of dental implant into the grafted area is recommended to mitigate subsequent resorption of the bone graft.

A RETROSPECTIVE STUDY OF BILATERAL ALVEOLAR BONE GRAFTING

To evaluate the treatment results of bilateral alveolar bone grafting (BABG) in patients with bilateral complete clefts of lip and palate. [WT5”BX] Methods.[WT5”BZ] A retrospective study was performed in 66 bilateral complete cleft lip and palate patients who received the procedure of BABG, among them 15 were primary BABG and 51 were secondary BABG. The patients were further divided into three groups according to age and eruption stage of the canine at the time of surgery. The result of BABG was evaluated on the radiographs. [WT5”BX] Results.[WT5”BZ] (1)The overall success rate of BABG was 75 0%, with 83 3% and 72 5% for primary and secondary BABG respectively; (2)The marginal bone level was found to be significantly higher in the youngest age group than in the other groups both for primary and secondary BABG; (3)For both primary and secondary BABG, Group C (patients’ age more than 16 years) had the least optimal success rate, with 66 7% and 65 4% respectively. [WT5”BX] Conclusion.[WT5”BZ] Simultaneous primary palate repair and BABG is safe and feasible procedure for treating unoperated bilateral complete cleft lip and cleft palate patients. For both primary and secondary BABG, significantly better results can be achieved if the operation is performed before eruption of the canine.

Artificial dermis combined with skin grafting for the treatment of hand skin and soft tissue defects and exposure of bone and tendon

BACKGROUND The recovery time of hand wounds is long,which can easily result in chronic and refractory wounds,making the wounds unable to be properly repaired.The treatment cycle is long,the cost is high,and it is prone to recurrence and disability.Double layer artificial dermis combined with autologous skin transplantation has been used to repair hypertrophic scars,deep burn wounds,exposed bone and tendon wounds,and post tumor wounds.AIM To investigate the therapeutic efficacy of autologous skin graft transplantation in conjunction with double-layer artificial dermis in treating finger skin wounds that are chronically refractory and soft tissue defects that expose bone and tendon.METHODS Sixty-eight chronic refractory patients with finger skin and soft tissue defects accompanied by bone and tendon exposure who were admitted from July 2021 to June 2022 were included in this study.The observation group was treated with double layer artificial dermis combined with autologous skin graft transplantation(n=49),while the control group was treated with pedicle skin flap transplantation(n=17).The treatment status of the two groups of patients was compared,including the time between surgeries and hospital stay.The survival rate of skin grafts/flaps and postoperative wound infections were evaluated using the Vancouver Scar Scale(VSS)for scar scoring at 6 mo after surgery,as well as the sensory injury grading method and two-point resolution test to assess the recovery of skin sensation at 6 mo.The satisfaction of the two groups of patients was also compared.RESULTS Wound healing time in the observation group was significantly longer than that in the control group(P<0.05,27.92±3.25 d vs 19.68±6.91 d);there was no significant difference in the survival rate of skin grafts/flaps between the two patient groups(P>0.05,95.1±5.0 vs 96.3±5.6).The interval between two surgeries(20.0±4.3 d)and hospital stay(21.0±10.1 d)in the observation group were both significantly shorter than those in the control group(27.5±9.3 d)and(28.4±17.7 d),respectively(P<0.05).In comparison to postoperative infection(23.5%)and subcutaneous hematoma(11.8%)in the control group,these were considerably lower at(10.2%)and(6.1%)in the observation group.When comparing the two patient groups at six months post-surgery,the excellent and good rate of sensory recovery(91.8%)was significantly higher in the observation group than in the control group(76.5%)(P<0.05).There was also no statistically significant difference in two point resolution(P>0.05).The VSS score in the observation group(2.91±1.36)was significantly lower than that in the control group(5.96±1.51),and group satisfaction was significantly higher(P<0.05,90.1±6.3 vs 76.3±5.2).CONCLUSION The combination of artificial dermis and autologous skin grafting for the treatment of hand tendon exposure wounds has a satisfactory therapeutic effect.It is a safe,effective,and easy to operate treatment method,which is worthy of clinical promotion.

Mid-term follow-up of one-stage posterior debridement, intertransverse process bone grafting and screw-rod system fixation for Brucella spondylitis of the lumbar spine

Objective:To investigate the short-term and medium-term efficacy of one-stage posterior debridement,intertransverse process bone grafting and screw-rod system fixation in the treatment of Brucella spondylitis of the lumbar spine.Method:156 cases of Brucella spondylitis of lumbar spine were selected and divided into experimental group(n=80)and combined group(n=76)according to different surgical methods.The experimental group was treated with one-stage posterior debridement,intertransverse process bone grafting and screw-rod system fixation.The combined group was treated with one-stage anterior debridement and intertransverse process bone grafting combined with posterior internal fixation.The operative indexes and clinical effects were compared between the two groups.Result:The operation time,intraoperative bleeding volume and time of landing after operation in the experimental group were less than those in the combined group,with statistical significance(P<0.05).VAS score,ODI index,Cobb angle and Frankel grade of nervous function in the two groups were significantly improved after 3 months and 36 months of treatment(P<0.05),but there was no significant difference between the two groups at the same time(P>0.05).There was no significant difference in the excellent and good rate between the two groups after 3 and 36 months of treatment(P>0.05).There was no recurrence of the lesion in both groups.The intertransverse process bone graft healed and the screw-rod system was well fixed.Conclusion:One-stage posterior debridement,intertransverse process bone grafting and screw-rod system fixation for treatment of Brucella spondylitis of lumbar spine are effective,with short operation time and less trauma,which are worthy of clinical promotion.

Evaluation of 4 different bone graft substitutes and autogenous bone grafting in root-end resection osteotomies after retrograde root-filling with Intermediate Restorative Material(IRM):An experimental study in dogs

Purpose: To investigate the periapical tissue response after root end filling with intermediate restorative material (IRM) and filling of the root-end resection bone defects with autogenous bone or a bone graft substitute in comparison to empty controls. Materials and Methods: Vital roots of the second, third and fourth mandibular premolars in six healthy mongrel dogs were apectomized. The root canals were prepared and sealed with IRM following a standardized surgical procedure. The resection bone defects were either filled with autogenous bone (PB) or one of the bone graft substitutes;CERAMENTTM|BONE VOID FILLER, ChronOS?, TigranTM PTG, Easygraft? CLASSIC or left empty. After 120 days the animals were sacrificed and the specimens were analyzed radiologically and histologically. Kruskal-Wallis and Mann-Whitney tests were performed for statistical evaluation. Results: 34 sections were analyzed histologically. The evaluation revealed a variation in the outcome amongst the tested options, regarding reestablishment of the periapical bone healing and inflammatory infiltration in the sections. According to the tested variables, there was no statistical significant difference between the materials when comparing all groups as a whole. When comparing individual materials to each other there was statistical differences among some of the tested materials. Conclusion: The healing outcome after periapical surgery of a five-wall resection defect could not be increased by infill with autogenous bone or bone graft substitutes. The most important factor for the healing outcome in periapical surgery is the quality of the root-end sealing. The healing outcome after some of the tested bone substitutes, might be improved by longer healing time.

Atlantoaxial joint fusion using anterior transarticular screw fixation and bone grafting for atlantoaxial joint instability

Objective To evaluate the clinical application of atlantoaxial joint fusion using anterior transarticular screw fixation and bone grafting for atlantoaxial joint instability. Methods Twenty-three cases of atlantoaxial joint instability were

Ability of bone graft substitutes to support the osteoprogenitor cells: An in-vitro study

AIM: To compare seven commercially available bone graft substitutes(BGS) in terms of these properties and without using any additional biological growth factors.METHODS: Porcine osteoprogenitor cells were loaded on seven commercially available BGS and allowed to proliferate for one week followed by osteogenic induction. Staining for live/dead cells as well as scanning electron microscopy(SEM) was carried out to determine viability and cellular binding. Further outcome measures included alkaline phosphatase(ALP) assays with normalisation for DNA content to quantify osteogenic potential. Negative and positive control experiments were carried out in parallel to validate the results.RESULTS: Live/dead and SEM imaging showed higher viability and attachment with β-tricalcium phosphate(β-TCP) than with other BGS(P < 0.05). The average ALP activity in nmol/mL(normalised value for DNA content in nmol/μg DNA) per sample was 657.58(132.03) for β-TCP, 36.22(unable to normalise) for calcium sulphate, 19.93(11.39) for the Hydroxyapatite/Tricalcium Phosphate composite, 14.79(18.53) for polygraft, 13.98(8.15) for the highly porous β-Tricalcium Phosphate, 5.56(10.0) for polymers, and 3.82(3.8) for Hydroxyapatite.CONCLUSION: Under the above experimental conditions, β-TCP was able to maintain better the viability of osteoprogenitor cells and allow proliferation and differentiation(P < 0.05).

Bone graft substitutes for spine fusion: A brief review

Bone graft substitutes are widely used in the field of orthopedics and are extensively used to promote vertebral fusion. Fusion is the most common technique in spine surgery and is used to treat morbidities and relieve discomfort. Allograft and autograft bone substitutes are currently the most commonly used bone grafts to promote fusion. These approaches pose limitations and present complications to the patient. Numerous alternative bone graft substitutes are on the market or have been developed and proposed for application. These options have attempted to promote spine fusion by enhancing osteogenic properties. In this review, we reviewed biology of spine fusion and the current advances in biomedical materials and biological strategies for application in surgical spine fusion. Our findings illustrate that, while many bone graft substitutes perform well as bone graft extenders, only osteoinductive proteins(recombinant bone morphogenetic proteins-2 and osteogenic protein-1) provide evidence for use as both bone enhancers and bone substitutes for specific types of spinal fusion. Tissue engineered hydrogels, synthetic polymer composites and viral based gene therapy also holds the potential to be used for spine fusion in future, though warrants further investigation to be used in clinical practice.

Acetabular Reconstruction with Massive Allograft Shaped to the Cavity and Kerboull-Type Acetabular Reinforcement Device for Multiple Failures of Impaction Bone Graft: A Case Report

Acetabular component revision in the presence of severe bone loss is difficult for reconstructing an acetabular component in the anatomical hip center. Various treatment options are available, although often the acetabular defect cannot be corrected with a single option alone. Precise assessment of the bone loss and a suitable combination of methods are needed. Here we report a case of multiple failures with impaction bone grafting reconstruction for an acetabular bone defect of American Academy of Orthopedic Surgeons classification type III. We finally reconstructed the acetabulum with three femoral head allografts and a Kerboull-type acetabular reinforcement device. The allograft was a casted, jet-type helmet-like shape. A year later the patient was able to walk without a cane and perform light agricultural work. Accurate evaluation of the acetabular bone loss and appropriate reconstruction is important.

TrkA regulates the regenerative capacity of bone marrow stromal stem cells in nerve grafts

We previously demonstrated that overexpression of tropomyosin receptor kinase A(TrkA)promotes the survival and Schwann celllike differentiation of bone marrow stromal stem cells in nerve grafts,thereby enhancing the regeneration and functional recovery of the peripheral nerve.In the present study,we investigated the molecular mechanisms underlying the neuroprotective effects of TrkA in bone marrow stromal stem cells seeded into nerve grafts.Bone marrow stromal stem cells from Sprague-Dawley rats were infected with recombinant lentivirus vector expressing rat TrkA,TrkA-shRNA or the respective control.The cells were then seeded into allogeneic rat acellular nerve allografts for bridging a 1-cm right sciatic nerve defect.Then,8 weeks after surgery,hematoxylin and eosin staining showed that compared with the control groups,the cells and fibers in the TrkA overexpressing group were more densely and uniformly arranged,whereas they were relatively sparse and arranged in a disordered manner in the TrkA-shRNA group.Western blot assay showed that compared with the control groups,the TrkA overexpressing group had higher expression of the myelin marker,myelin basic protein and the axonal marker neurofilament 200.The TrkA overexpressing group also had higher levels of various signaling molecules,including TrkA,pTrkA(Tyr490),extracellular signal-regulated kinases 1/2(Erkl/2),pErk1/2(Thr202/Tyr204),and the anti-apoptotic proteins Bcl-2 and Bcl-xL.In contrast,these proteins were downregulated,while the pro-apoptotic factors Bax and Bad were upregulated,in the TrkA-shRNA group.The levels of the TrkA effectors Akt and pAkt(Ser473)were not different among the groups.These results suggest that TrkA enhances the survival and regenerative capacity of bone marrow stromal stem cells through upregulation of the Erk/Bcl-2 pathway.All procedures were approved by the Animal Ethical and Welfare Committee of Shenzhen University,China in December 2014(approval No.AEWC-2014-001219).