Delayed intervention for hip fracture and dislocation is a core risk factor for osteonecrosis of the femoral head (ONFH). According to the latest research, the incidence of ONFH in patients with acetabular fracture combined with hip dislocation can reach 30%-40%, and this risk increases 1.89 times if treatment is delayed for more than 3 weeks. This presents a clinical challenge in polytrauma management, where systemic stability must be balanced against timely hip injury intervention under the principles of damage control orthopedics. This study reports the case of a 45-year-old man with severe polytrauma following a traffic accident. He suffered from extensive soft tissue injuries, bilateral pelvic and right acetabular comminuted fractures, central right hip dislocation, and multiple open injuries that required priority treatment. Repair of the right comminuted acetabular fracture with central hip dislocation was delayed for 53 days, ultimately resulting in secondary ONFH and requiring total hip arthroplasty (THA). Imaging examinations confirmed an Orthopaedic Trauma Association (OTA) acetabular fracture type 62-C, with a 2.5-cm displacement of the femoral head into the pelvic cavity. Staged interventions-including damage control, wound repair, hip reconstruction, and THA-were performed. At the 30-month follow-up, the patient demonstrated significant improvement in hip function [Harris Hip Score increased from 45 to 88 points, visual analog scale pain score reduced to 1 point]. This study systematically discusses the staged treatment strategies for polytrauma, surgical techniques for chronic hip fractures, and key considerations for the prevention and treatment of post-traumatic ONFH, thereby providing a practical clinical management framework for the staged treatment of similar complex polytrauma cases complicated by chronic hip injuries.

Tissue engineering provides a promising avenue for treating meniscus defects. In this study, a novel polycaprolactone (PCL)/collagen type I (COL I) meniscus scaffold was fabricated using low temperature deposition manufacturing (LDM) 3D printing technology. The scaffold had a ring and radial fiber structure, and its composition and structure were double bionic of the natural meniscus. In vitro experiments showed that the scaffold had good biological properties, which could promote the proliferation of meniscus fibrochondrocytes (MFCs) and increase the secretion of collagen and glycosaminoglycan. Moreover, the scaffold had excellent mechanical properties and could withstand various stress loads from the femur and tibia. The integrity of the scaffold structure was maintained to provide sufficient time and space for tissue regeneration. The PCL/ COL I scaffold has shown good therapeutic effect in a rabbit meniscus defect model and promotes meniscus regeneration. The results of experiments in rabbits suggest that the scaffold may recruit stem cells and differentiate into fibrochondrocytes in the knee joint, which needs to be verified by further experiments. This study introduces a method of fabricating a new structural composition double bionic meniscus scaffold by LDM technology and verifies its ability to promote cell proliferation, increase the secretion of the extracellular matrix of fibrocartilage, and regulate the microenvironment of cell growth. In addition, this scaffold has achieved good results in repairing meniscus defects in small animal models. Our findings strongly indicate that the PCL/COL I biomimetic meniscus scaffold prepared using 3D-LDM technology holds great promise for repairing and regenerating damaged menisci.

OBJECTIVES:This study aims to characterize a three-dimensional-printed hydroxyapatite (HA)/polycaprolactone (PCL) scaffold and assess its biocompatibility both in vitro and in vivo. METHODS:A bionic, porous HA/PCL scaffold was fabricated using 3D printing, and its microstructure, porosity, hydrophilicity, and mechanical properties were evaluated through scanning electron microscopy and various assays. Bone marrow mesenchymal stem cells (BMSCs) and vascular endothelial progenitor cells (VEPCs) were co-cultured with the scaffold, and their proliferation and osteogenic differentiation were assessed using the Cell Counting Kit-8, ALP assays, and alizarin red staining. Osteogenic marker expression was analyzed via qRT-PCR. In vivo bone regeneration was evaluated through histological analysis of H&E and Masson's trichrome staining in a rat cranial defect model. RESULTS:The average pore size of the scaffold was 462.00 ± 100.389 μm, with a porosity of 53%, a water absorption expansion rate of 5.10%, a contact angle of 94.55°, an elastic modulus of 53.82 MPa, and a compressive strength of 6.10 MPa. ALP activity and qRT-PCR analysis of osteogenic markers (BMP2, OCN, Runx2) showed significant upregulation in cells co-cultured with the scaffolds. In vivo experiments demonstrated enhanced bone regeneration and collagen deposition in the HA/PCL scaffold group. CONCLUSION:The results suggest that the HA/PCL scaffold promotes osteogenic differentiation and bone regeneration, making it suitable for bone tissue engineering applications.

BackgroundAlthough artificial hip and knee arthroplasty has been widely used, the incidence of perioperative complications remains relatively high due to factors such as long operation time and large surgical incisions. However, the Hospital Frailty Risk Score (HFRS) clinical value for patients undergoing artificial hip and knee arthroplasty in China is not yet clear. This study aims to explore its clinical value in this population.ObjectiveTo explore predictive value of the HFRS in perioperative complications of artificial hip and knee arthroplasty in elderly patients.MethodsElderly patients who underwent artificial hip and knee arthroplasty in our hospital from March 2020 to March 2022 were selected as the study subjects. The patients were divided into the non-frail risk group (HFRS <5 points) and the frail risk group (HFRS ≥5 points) on the basis of the literature grading method. 5-factor modified frailty index (mFI-5) and Charlson Comorbidity Index (CCI) scores were assessed. General data including age, sex, ASA classification, preoperative course, and surgical time were collected through the electronic medical record system. The occurrence of postoperative deep venous thrombosis, periprosthetic infection, hematoma, anemia, and overall complications was recorded. Hospitalization days, surgical costs, and total treatment costs were also calculated for all patients.ResultsThere were no significant differences in age, sex, ASA classification, preoperative course, or surgical time between the two groups (p > 0.05). The frail risk group had significantly higher mFI-5 and CCI scores (p < 0.05). This group also had a higher incidence of deep venous thrombosis and overall complications (p < 0.05), but similar rates of periprosthetic infection, hematoma, and anemia (p > 0.05). ROC analysis showed HFRS had the highest predictive value for postoperative complications (AUC = 0.851) compared to mFI-5 (0.786) and CCI (0.739). Surgical costs were similar (p > 0.05), but the frail group had longer hospital stays and higher total treatment costs (p < 0.05).ConclusionHFRS has better predictive value for perioperative complications in elderly patients undergoing artificial hip and knee arthroplasty compared to mFI-5 and CCI scores, and it can be used for predicting perioperative complications in elderly patients with this surgery.

目的 探讨股骨重建髓内钉治疗股骨转子下骨折的疗效.方法 采用股骨重建髓内钉治疗42 例股骨转子下骨折患者.记录手术情况、骨折愈合情况、术后并发症发生情况,末次随访时采用髋关节功能Harris评分、膝关节功能HSS评分评价疗效.结果 患者均获得随访,时间15～20 个月.手术时间44～91(68.88±13.28)min,术中出血量40～120(83.21±17.42)ml,术后住院时间3～8(5.31±1.16)d.38 例骨折愈合时间为 3～6(4.03±0.72)个月,2 例骨折在术后第10、11 个月愈合,2 例骨折不愈合经再次手术后愈合.术后切口感染2 例,中重度贫血(血红蛋白<70 g/L)4 例,螺钉退钉切出2 例,髋内翻畸形1 例,压疮2 例.末次随访时,髋关节功能Harris评分为78～97(93.86±3.14)分,其中优39 例,良1 例,可2 例,优良率为95.24％;膝关节功能HSS评分为91～97(94.69±1.52)分,42 例均为优.结论 股骨重建髓内钉是治疗股骨转子下骨折良好的内固定方式,尤其适用于中青年患者.

目的:探讨桥接钉棒组合式内固定对开放性胫骨干骨折二期更换内固定的疗效.方法:统计本院2015年6月至2021年3月以桥接钉棒组合式内固定作为二期内固定方式的17例Gustilo Ⅱ、Ⅲ度开放性胫骨干骨折患者,分析术前、术中、术后的观察指标,以及术后膝关节功能HSS评分、踝关节功能Baird评分、Johner-Wruh疗效评分,以及术后并发症等.结果:纳入病例随访时间均在8个月及以上,均得到完整随访,平均随访时间(14.650±1.835)个月,其中1例发生骨折不愈合,1例畸形愈合.Johner-Wruh评分疗效的优良率为94.12％,术后6个月踝关节功能Baird评分、膝关节功能HSS评分分别达到(90.530±1.875)分和(83.000±1.969)分,术后并发症发生率低.结论:对于Gustilo Ⅱ、Ⅲ度开放性胫骨干骨折二期更换内固定,桥接钉棒组合式内固定为良好的选择,值得推广应用.

Background The repair of large bone defects is a great challenge for orthopedics. Although the development of three-dimensional (3D) printed titanium alloy (Ti6Al4V) implants with optimized the pore structure have effectively promoted the osseointegration. However, due to the biological inertia of Ti6Al4Vsurface and the neglect of angiogenesis, some patients still suffer from postoperative complications such as dislocation or loosening of the prosthesis. Methods The purpose of this study was to construct 3D printed porous Ti6Al4V scaffolds filled with bone marrow mesenchymal stem cells (BMSC) and endothelial progenitor cells (EPC) loaded hydrogel and evaluate the efficacy of this composite implants on osteogenesis and angiogenesis, thus promoting osseointegration. Results The porosity and pore size of prepared 3D printed porous Ti6Al4V scaffolds were 69.2 ± 0.9 % and 593.4 ± 16.9 μm, respectively, which parameters were beneficial to bone ingrowth and blood vessel formation. The BMSC and EPC filled into the pores of the scaffolds after being encapsulated by hydrogels can maintain high viability. As a cell containing composite implant, BMSC and EPC loaded hydrogel incorporated into 3D printed porous Ti6Al4V scaffolds enhancing osteogenesis and angiogenesis to repair bone defects efficiently. At the transcriptional level, the composite implant up-regulated the expression levels of the osteogenesis-related genes alkaline phosphatase ( ALP ) and osteocalcin ( OCN ), and angiogenesis-related genes hypoxia-inducible factor 1 alpha ( HIF-1α ), and vascular endothelial growth factor ( VEGF ). Conclusions Overall, the strategy of loading porous Ti6Al4V scaffolds to incorporate cells is a promising treatment for improving osseointegration.

Animal models play an important role in preclinical studies, especially in tissue engineering scaffolds for cartilage repair, which require large animal models to verify the safety and effectiveness for clinical use. The small ruminant models are most widely used in this field than other large animals because they are cost-effective, easy to raise, not to mention the fact that the aforementioned animal presents similar anatomical features to that of humans. This review discusses the experimental study of tissue engineering scaffolds for knee articular cartilage regeneration in small ruminant models. Firstly, the selection of these scaffold materials and the preparation process in vitro that have been already used in vivo are briefly reviewed. Moreover, the major factors influencing the rational design and the implementation as well as advantages and limitations of small ruminants are also demonstrated. As regards methodology, this paper applies principles and methods followed by most researchers in the process of experimental design and operation of this kind. By summarizing and comparing different therapeutic concepts, this paper offers suggestions aiming to increase the effectiveness of preclinical research using small ruminant models and improve the process of developing corresponding therapies.

目的 探讨大黄素(emodin,DHS)对去卵巢大鼠骨量流失的影响,并探索可能的机制.方法 通过双侧去卵巢建立骨质疏松大鼠模型;随后随机分为假手术组(Sham)、去卵巢组(OVX)以及大黄素组(DHS),每组10只;其中DHS组大鼠接受大黄素[90 mg/(kg·d)]治疗12周;待治疗结束后使用Micro-CT、HE染色切片、骨代谢指标、以及蛋白质印迹观察治疗效果以及可能的机制.结果 治疗12周后,与OVX组相比,Micro-CT和HE染色切片结果显示DHS组的大鼠骨小梁数量和骨密度得到明显改善.DHS组大鼠BMD、TV/BV、Tb.N、Tb.Th和Tb.Sp较OVX组明显改善(P<0.05).与OVX组相比,DHS组的BALP水平明显升高(P<0.05);而TRACP-5b和β-CTX水平显著降低(P<0.05).和OVX组比较,DHS组OPG表达水平上调(P<0.05),而RANKL和β2AR表达水平下调(P<0.05).结论 大黄素可以通过降低 β2AR表达和激活OPG/RANKL信号通路介导对去卵巢大鼠骨量流失的保护作用.

背景:有研究显示,不同内固定方式固定髋臼后柱骨折的生物力学存在差异.目的:模拟髋臼后柱骨折,评估3种固定方式固定髋臼后柱骨折后的稳定性.方法:取36个尸体半骨盆标本,建立髋臼后柱骨折模型,随机分3组固定:A组以髂坐短钢板固定,B组以传统后柱钢板固定,C组以髂坐长钢板固定,每组12个模型.模拟人体站立及坐立位时垂直方向加载力学载荷,采用图像位移法评估骨折断端的位移及生物力学稳定性.结果与结论:①站立位时,3组模型骨折断端相对位移与载荷大小呈正相关,相同载荷下3组间相对位移比较差异无显著性意义(P>0.05);加载1800 N载荷时,各组模型相对位移均未超过3 mm;②坐立位时,3组模型骨折断端相对位移与载荷大小呈正相关,相同载荷下3组间相对位移比较差异有显著性意义(P<0.05);相同载荷下,B组相对位移大于A、C组;A组100-500 N载荷下的相对位移大于C组,600 N载荷下的相对位移小于C组;③结果表明,髂坐钢板固定髋臼后柱骨折时能提供与传统后柱钢板同样的生物力学稳定性,固定结构刚度高,可满足术后康复需求.

目的 对比单髁置换术治疗膝关节自发性骨坏死与膝关节内侧骨关节炎的临床疗效.方法 回顾性分析我科2017年1月至2019年1月使用单髁关节置换术治疗符合诊断的膝关节自发性骨坏死(spontaneous osteonecro-sis of the knee,SONK)患者20例20膝(SONK组),男4例,女16例,年龄61～83岁,平均(71.9±8.2)岁.根据年龄、性别、身体质量指数筛选出相匹配的同期使用单髁置换术治疗膝关节内侧骨关节炎(medial compartment osteoar-thritis,MOA)患者20例20膝(MOA组),男4例,女16例,年龄63～79岁,平均(72.5±8.2)岁.记录两组术后并发症发生情况、术前及末次随访时美国特种外科医院膝关节评分(hospital for special surgery,HSS)、牛津大学膝关节评分(Oxford knee score,OKS)、膝关节最大活动度(range of motion,ROM)、股胫角、髋膝踝角.结果 40例均获随访,随访时间12～32个月,平均(24.2±17.4个)个月,骨坏死组1例出现假体松动,骨关节炎组1例出现不明原因疼痛,两组患者皆无感染、深静脉血栓形成等并发症发生.两组患者末次随访时膝关节OKS评分、KSS评分、膝关节活动度均较术前明显改善,差异有统计学意义(P＜0.05),但组间对比差异无统计学意义(P＞0.05);SONK组股胫角、髋膝踝角均较术前明显改善,差异有统计学意义(P＜0.05).结论 单髁置换术治疗膝关节自发性骨坏死具有创伤小、术后恢复快、术后本体感觉存在等优点,中短期疗效满意,与治疗膝关节内侧骨关节炎具有相似的临床疗效.

ObjectiveTo investigate the effectiveness of two surgical approaches in the treatment of type Ⅳ Pipkin fracture.MethodsThe clinical data of 15 patients with type Ⅳ Pipkin fracture treated surgically between July 2013 and June 2018 were retrospectively analyzed. According to different surgical approaches, they were divided into group A (8 cases, using K-L posterior approach) and group B (7 cases, using greater trochanter osteotomy approach). There was no significant difference in gender, age, cause of injury, and interval from injury to operation between the two groups ( P>0.05). The incision length, operation time, intraoperative blood loss, hospital stay, fracture healing time, and complications of the two groups were recorded. Hip joint function recovery was evaluated according to Thompson-Epstein functional evaluation system.ResultsAll the 15 patients were followed up 1-5 years, with an average of 2.5 years. There was no significant difference in operation time between the two groups ( t=14.681, P=0.100); the incision length, intraoperative blood loss, and fracture healing time in group A were all greater than those in group B, and the hospital stay was shorter than that in group B, showing significant differences ( P<0.05). In group A, 1 patient presented hip pain, clasthenia, and limited mobility after operation, 1 patient presented ossifying myositis, 1 patient presented osteonecrosis of the femoral head, 1 patient presented fat liquefaction of incision, and 1 patient presented sciatica, with a complication incidence of 62.5%. Postoperative hip pain occurred in 1 patient and ossifying myositis in 2 patients in group B, with a complication incidence of 42.9%. There was no significant difference in the incidence of complications between the two groups ( χ 2=-0.735, P=0.462). At last follow-up, according to Thompson-Epstein functional evaluation system, the results in group A were excellent in 3 cases, good in 2 cases, fair in 2 cases, and poor in 1 case, with an excellent and good rate of 62.5%; in group B, the results were excellent in 4 cases, good in 2 cases, and fair in 1 case, and the excellent and good rate was 85.7%. There was no significant difference in good and fair rate between the two groups ( χ 2=-0.990, P=0.322).ConclusionK-L posterior approach is more convenient in the fracture treatment during operation, but it has greater trauma, greater vascular damage, and more blood loss. The greater trochanter osteotomy approach can better protect the blood supply of femoral head, shorten the operation time, reduce intraoperative blood loss, and reduce postoperative complications. It is an ideal way in the surgical treatment of type Ⅳ Pipkin fracture.

The aim of this study was to evaluate the clinical and functional outcomes of patients with large post-traumatic tibial bone defects managed by double-level bone transport using the Ilizarov technique and compare it with one-level bone transport technique. A retrospective cohort study was conducted on 26 patients with open tibial fracture from January 2010 to January 2017. All cases were Gustilo III. Depending on the site of osteotomy, the patients were divided into single-level (n = 13) and double-level groups (n = 13). The bone transport time, consolidation time of the distraction gap, docking site healing time, external fixation time, external fixation index, soft tissue defect area, soft tissue growth index, operating time, and surgical bleeding volume were recorded and compared between the two groups. Bone and functional results were evaluated according to the Association for the Study and Application of the Method of Ilizarov (ASAMI) criteria. The mean duration of follow-up was 28.5 ± 5.8 months (range 13–38 months) since the Orthofix fixator was removed, all patients achieved complete union in the docking site and consolidation in the regenerate bone; moreover, the wound was closed The mean bone defect length after debridement was 7.2 cm (range 5.8–9.0 cm) in single-level group vs. 10.7 cm (range 7.5–15.0 cm) in the double-level group (P < 0.05). The mean docking site healing time was 10.85 ± 1.52 months in the single-level group vs. 8.93 ± 2.29 months in the double-level group (P < 0.05); external frame time was 18.06 months (range 15–20 months) in single-level group vs. 12.71 months (range 9.5–16.0 months) in the double-level group (P < 0.05); external fixation index was 2.52 months/cm (range 2.15–2.94 months/cm) versus 1.22 months/cm (range 0.96–1.67 months/cm) in double-level group (P < 0.01); and soft tissue growth index was 0.29 months/cm2 (range 0.21–0.45 months/cm2) in the single-level group versus 0.62 months/cm2 (range 0.47–0.86 months/cm2) in the double-level group (P < 0.01). According to the ASAMI classification, the clinical and functional results in the double-level group were better than in the single-level group. The Ilizarov technique of double-level bone transport with Orthofix external fixator can be used successfully to repair and reconstruct the tibial bone loss and accompanying soft tissue defect.

目的 分析三维重建技术下成人髋臼后柱内髂坐钢板置钉的安全区域及安全角度.方法 收集2018年12月～2019年6月在我院接受治疗及检查的50例成年患者的正常骨盆CT数据,利用三维重建技术分别计算不同性别成年患者髋臼后柱内髂坐钢板置钉的安全区域及安全角度.结果 50例患者的平均安全区宽度(d)为(27.52±4.16)mm,闭孔管最高点至坐骨大切迹之间的平均垂直距离(w)为(45.87±3.69)mm,d/w值为(0.60±0.08),男性与女性的w值相比差异无统计学意义(P>0.05),但男性的d值和d/w值均明显高于女性(P<0.05);50例患者的内髂坐钢板置钉平均安全角度分别为∠A(88.93±4.32)°、∠B(76.97±4.11)°和∠C(64.38±4.58)°,男性的∠D平均角度为(55.96±4.57)°,男性与女性的∠B值相比差异无统计学意义(P>0.05),但男性的∠A值明显低于女性(P<0.05),且∠C值明显高于女性(P<0.05).结论 不同性别成年患者的髋臼后柱内髂坐钢板置钉安全区域和安全角度不同,临床中需根据患者性别的不同选择不同的安全角度置钉,以减少螺钉穿出风险.

背景:近年来国外使用超临界流体进行生物材料处理的研究较多,但是超临界流体应用于骨组织清洗的研究少见,国内相关报道更少.目的:评估超临界二氧化碳萃取技术处理猪股骨松质骨的有效性及对骨生物学性能的影响.方法:分别制备超临界二氧化碳萃取前(对照组)及萃取后猪股骨骨块(实验组),检测两组骨密度、微观结构、最大抗压强度、弹性模量、骨组织组成成分、胶原含量与组织学分析.将骨髓间充质干细胞分别接种于两组骨块上,培养1 d后,扫描电镜观察材料骨小梁微孔结构及骨材料-细胞复合物中细胞黏附及生长情况.将两组骨块分别植入SD大鼠皮下,术后1,2,4周组织学观察皮下包埋炎症反应.动物实验方案已经解放军总医院伦理委员会批准.结果与结论:①两组材料孔径大小、骨密度、最大抗压强度、弹性模量、胶原含量比较差异均无显著性意义(P>0.05);②扫描电镜显示,对照组材料孔隙连通欠佳,有软组织残留;实验组材料孔隙相互连通、结构完整;③傅里叶红外光谱及X射线衍射分析显示,两组骨组织材料具有相似的吸收峰及衍射峰,热重分析显示超临界二氧化碳萃取可减少骨组织水分含量;④苏木精-伊红染色显示实验组骨无软组织残留,骨陷凹内细胞残留明显减少,对照组有软组织及细胞残留;天狼星红及改良Masson染色显示实验组骨胶原结构完整,胞质成分减少,对照组胞质成分残留明显;⑤扫描电镜显示,对照组骨无明显细胞黏附,实验组骨可见明显细胞黏附生长;⑥实验组骨组织植入皮下的血管周围炎症反应明显轻于对照组骨组织;⑦结果表明,超临界二氧化碳萃取技术是一种有效、环保的骨组织处理技术,在不影响其胶原结构及含量、力学性能的基础上,能够有效去除猪股骨松质骨细胞及软组织,保留骨孔隙结构完整,增加细胞黏附及生长,有效减低炎性排斥反应.

目的 探究血管内皮生长因子165(VEGF165)、骨形态发生蛋白(BMP2)双基因转染SD大鼠骨髓基质干细胞(BMSCs)及其基因表达与体外成骨能力.方法 提取SD大鼠胫骨骨髓,原代培养获得BMSCs并进行流式细胞学鉴定.通过脂质体(Lipofect-amine2000)介导VEGF165、BMP2基因转染SD大鼠BMSCs,并分为pIRES-hBMP2-hVEGF165转染组(双基因转染)、pIRES-hBMP2转染组(单基因转染)、pIRES-hVEGF165转染组(单基因转染)、空载转染组(空白对照).采用四甲基偶氮唑盐微量酶反应比色法(MTT)、酶联免疫吸附试验、组织学染色方法评估基因转染BMSCs的增殖情况、基因表达及体外成骨能力.结果 流式细胞鉴定培养的BMSCs表面Marker示CD44和CD90标志物阳性,CD34和CD45标志物为阴性,证实成功获取大鼠BMSCs.通过荧光显微镜观察各转染组BMSCs,24 h后可见绿色荧光发出,表明转染成功.MTT结果显示:随着时间的延长,各转染组BMSCs细胞的数量呈上升趋势,与未转染BMSCs的相比,细胞数量峰值无明显差异,证实转染后BMSCs生长情况良好.ELISA染色结果显示:pIRES-hBMP2-hVEGF165转染组BMP2蛋白及VEGF165蛋白水平较pIRES-hBMP2转染组和pIRES-hVEGF165转染组及空载转染组显著增高,差异有统计学意义(P<0.05).组织学染色观察发现pIRES-hBMP2-hVEGF165转染组细胞碱性磷酸酶、骨胶原蛋白及骨钙素阳性率明显高于pIRES-hBMP2转染组、pIRES-hVEGF165转染组、空载转染组,差异有统计学意义(P<0.05).结论 双基因转染后的BMSCs目的基因的表达良好,BMP2、VEGF165基因表达水平较单基因转染明显提高;双基因共转染SD大鼠BMSCs能够获得比单基因转染更优良的体外成骨能力.

Bioabsorbable magnesium alloys are becoming prominent materials for cardiovascular stents, as their desirable mechanical properties and favorable biosafety. However, the rapid corrosion of magnesium alloys under physiological conditions hinders their wider application as medical implant materials. Fluoride chemical conversion treatment is an effective and simple technique to improve the corrosion resistance for magnesium alloys. Despite previous literature reporting on fluoride chemical conversion treatment with hydrofluoric acid (HF) in different conditions, some defects are still present on the surface of the coating. In this study, we report on a two-step alkali-fluoride treatment of magnesium alloy by effectively removing the second phase in the substrate surface and form a dense and flawless magnesium fluoride (MgF2) coating to endow the magnesium alloy greater corrosion resistance. The results showed that the serious pitting corrosion caused by galvanic corrosion could be effectively prevented after removing of the second phase of the surface. In vivo tests in a rat subcutaneous implantation model showed that two-step alkali-fluoride-treated MgZnYNd alloy (MgZnYNd-A-F) uniformly corroded with a low corrosion rate. No subcutaneous gas cavities or significant inflammatory cell infiltration were observed for MgZnYNd-A-F in in vivo tests. The two-step alkali-fluoride treatment can significantly improve the corrosion resistance and biocompatibility of magnesium alloy, which has great potential in the application of vascular stents because of its simplicity and effectiveness.

OBJECTIVE:To manufacture a poly (lactic-co-glycolic acid) (PLGA) scaffold by low temperature deposition three-dimensional (3D) printing technology, prepare a PLGA/decellularized articular cartilage extracellular matrix (DACECM) cartilage tissue engineered scaffold by combining DACECM, and further investigate its physicochemical properties. METHODS:PLGA scaffolds were prepared by low temperature deposition 3D printing technology, and DACECM suspensions was prepared by modified physical and chemical decellularization methods. DACECM oriented scaffolds were prepared by using freeze-drying and physicochemical cross-linking techniques. PLGA/DACECM oriented scaffolds were prepared by combining DACECM slurry with PLGA scaffolds. The macroscopic and microscopic structures of the three kinds of scaffolds were observed by general observation and scanning electron microscope. The chemical composition of DACECM oriented scaffold was analyzed by histological and immunohistochemical stainings. The compression modulus of the three kinds of scaffolds were measured by biomechanical test. Three kinds of scaffolds were embedded subcutaneously in Sprague Dawley rats, and HE staining was used to observe immune response. The chondrocytes of New Zealand white rabbits were isolated and cultured, and the three kinds of cell-scaffold complexes were prepared. The growth adhesion of the cells on the scaffolds was observed by scanning electron microscope. Three kinds of scaffold extracts were cultured with L-929 cells, the cells were cultured in DMEM culture medium as control group, and cell counting kit 8 (CCK-8) was used to detect cell proliferation. RESULTS:General observation and scanning electron microscope showed that the PLGA scaffold had a smooth surface and large pores; the surface of the DACECM oriented scaffold was rough, which was a 3D structure with loose pores and interconnected; and the PLGA/DACECM oriented scaffold had a rough surface, and the large hole and the small hole were connected to each other to construct a vertical 3D structure. Histological and immunohistochemical qualitative analysis demonstrated that DACECM was completely decellularized, retaining the glycosaminoglycans and collagen typeⅡ. Biomechanical examination showed that the compression modulus of DACECM oriented scaffold was significantly lower than those of the other two scaffolds ( P<0.05). There was no significant difference between PLGA scaffold and PLGA/DACECM oriented scaffold ( P>0.05). Subcutaneously embedded HE staining of the three scaffolds showed that the immunological rejections of DACECM and PLGA/DACECM oriented scaffolds were significantly weaker than that of the PLGA scaffold. Scanning electron microscope observation of the cell-scaffold complex showed that chondrocytes did not obviously adhere to PLGA scaffold, and a large number of chondrocytes adhered and grew on PLGA/DACECM oriented scaffold and DACECM oriented scaffold. CCK-8 assay showed that with the extension of culture time, the number of cells cultured in the three kinds of scaffold extracts and the control group increased. There was no significant difference in the absorbance ( A) value between the groups at each time point ( P>0.05). CONCLUSION:The PLGA/DACECM oriented scaffolds have no cytotoxicity, have excellent physicochemical properties, and may become a promising scaffold material of tissue engineered cartilage.

The inflammatory response to chronic injury affects tissue regeneration and has become an important factor influencing the prognosis of patients. In previous stem cell treatments, it was revealed that stem cells not only have the ability for direct differentiation or regeneration in chronic tissue damage but also have a regulatory effect on the immune microenvironment. Stem cells can regulate the immune microenvironment during tissue repair and provide a good soil for tissue regeneration. In the current study, the regulation of immune cells by mesenchymal stem cells (MSCs) in the local tissue microenvironment and the tissue damage repair mechanisms are revealed. The application of the concepts of seed and soil has opened up new research avenues for regenerative medicine. Tissue engineering (TE) technology has been used in multiple tissues and organs using its biomimetic and cellular cell abilities, and scaffolds are now seen as an important part of building seed cell microenvironments. The effect of tissue engineering techniques on stem cell immune regulation is related to the shape and structure of the scaffold, the preinflammatory microenvironment constructed by the implanted scaffold, and the material selection of the scaffold. In the application of scaffold, stem cell technology has important applications in cartilage, bone, heart, and liver and other research fields. In this review, we separately explore the mechanism of MSCs in different tissue and organs through immunoregulation for tissue regeneration and MSC combined with 3D scaffolds to promote MSC immunoregulation to repair damaged tissues.

Heterogeneity of mesenchymal stem cells (MSCs) influences the cell therapy outcome and the application in tissue engineering. Also, the application of subpopulations of MSCs in cartilage regeneration remains poorly characterized. CD146+ MSCs are identified as the natural ancestors of MSCs and the expression of CD146 are indicative of greater pluripotency and self-renewal potential. Here, we sorted a CD146+ subpopulation from adipose-derived mesenchymal stem cells (ADSCs) for cartilage regeneration. Methods: CD146+ ADSCs were sorted using magnetic activated cell sorting (MACS). Cell surface markers, viability, apoptosis and proliferation were evaluated in vitro. The molecular signatures were analyzed by mRNA and protein expression profiling. By intra-articular injections of cells in a rat osteochondral defect model, we assessed the role of the specific subpopulation in cartilage microenvironment. Finally, CD146+ ADSCs were combined with articular cartilage extracellular matrix (ACECM) scaffold for long term (3, 6 months) cartilage repair. Results: The enriched CD146+ ADSCs showed a high expression of stem cell and pericyte markers, good viability, and immune characteristics to avoid allogeneic rejection. Gene and protein expression profiles revealed that the CD146+ ADSCs had different cellular functions especially in regulation inflammation. In a rat model, CD146+ ADSCs showed a better inflammation-modulating property in the early stage of intra-articular injections. Importantly, CD146+ ADSCs exhibited good biocompatibility with the ACECM scaffold and the CD146+ cell-scaffold composites produced less subcutaneous inflammation. The combination of CD146+ ADSCs with ACECM scaffold can promote better cartilage regeneration in the long term. Conclusion: Our data elucidated the function of the CD146+ ADSC subpopulation, established their role in promoting cartilage repair, and highlighted the significance of cell subpopulations as a novel therapeutic for cartilage regeneration.