国产镍钛合金血管内裸支架治疗囊形腹主动脉瘤的实验研究

目的 研究、观察国产血管内支架治疗犬腹主动脉瘤的疗效。方法 采用简单随机分组方法，将健康杂种犬32只随机分为4组，每组8只。组1；对照组，未置入支架；组2：实验组，腹主动脉前壁纵行切口长度≤1cm，置入支架治疗；组3：实验组，腹主动脉前壁纵行切口长度＞1cm且≤2cm，置入支架治疗；组4：实验组，腹主动脉前壁纵行切口长度≥3cm，置入支架治疗。外科方法建立腹主动脉瘤模型后2周行介入治疗。术后每个月行增强CT检查；第6个月处死时，行腹主动脉造影检查。结果 组1在6个月观察期内，CT和腹主动脉造影检查均示瘤腔存在。组2于第1个月CT检查时发现有1只犬瘤腔闭合；第2个月CT检查时有4只犬瘤腔闭合；第3个月有2只犬瘤腔闭合；条4个月有1只犬瘤腔闭合；第6个月腹主动脉造影检查也证实瘤腔闭合。组3CT检查和腹主动脉造影检查发现每只犬均残留有1个小瘤腔，且瘤壁呈向心性增厚。组4CT检查和腹主动脉造影检查发现每只犬均显示有1个大瘤腔。32只犬的腹主动脉均通畅。结论 国产镍钛合金血管内裸支架，对瘤颈直径≤1cm的腹主动脉瘤有治疗作用；对瘤颈直径＞1cm且≤2cm者，可防止动脉瘤继续扩张和迟发破裂；对瘤颈直径≥3cm者则无任何治疗作用。     

脱钙骨基质与左旋聚乳酸/聚磷酸钙纤维对骨髓间充质干细胞黏附作用的比较

目的探讨左旋聚乳酸／聚磷酸钙纤维（PLLA／CPPf）与同种异体的脱钙骨基质（DBM）对BMSCs黏附作用的差异，为构建组织工程骨提供理想的支架材料。方法用扫描电镜观察两种支架材料的孔径；通过测吸水率比较其亲水性。将普通培养瓶培养的第3代BMSCs分别成骨诱导培养1周后，在体外分别与PLLA／CPPf和同种异体的DBM复合构建组织工程骨，于构建后10h计算细胞黏附率，并用扫描电镜观察比较两种支架材料对BMSCs黏附作用的差异。构建后每天在相差显微镜下观察BMSCs在两种支架材料上的生长情况，构建后第10天再行扫描电镜观察BMSCs在两种支架材料上的生长情况。结果DBM的孔径明显较PLLA／CPPf的大，孔隙率高，体外构建后10hDBM组的细胞黏附率为（91．3±8．2）％，PLLA/CPPf组为（82．2±7．7）％，两者之间差异具有统计学意义（P〈0．05）。DBM组于术后第3天网孔间出现细胞外基质，且随着时间的推移，基质变得稠密，而PLLA／CPPf的细胞外基质鲜见；第10天的扫描电镜也证实DBM组的细胞在支架材料上数量多，且细胞外的基质分泌较多。结论DBM较PLLA／CPPf更适于BMSCs的黏附生长，是理想的组织工程支架材料。     

纵隔纤维组织和纤维组织细胞肿瘤CT诊断

目的　探讨纵隔纤维组织和纤维组织细胞肿瘤CT诊断。方法　分析经病理证实 12例纵隔纤维组织和纵隔纤维组织细胞肿瘤CT表现。结果　左后上纵隔纤维瘤病 1例 ,包裹主动脉。孤立性纤维瘤 3例 ,分别位于前中后纵隔 ,直径 4～ 6cm ,纵隔一侧突出。纤维肉瘤 3例 ,直径 >7cm。后纵隔纤维黄色瘤 2例 ,密度较低 (CT值 <2 0HU)。恶性纤维组织细胞瘤前纵隔 1例 ,后纵隔 2例 ,直径 >10cm。结论　纵隔纤维源性肿瘤后纵隔多发 ,包膜完整 ,生长缓慢 ,纵隔纤维瘤病及孤立性纤维瘤表现较特异 ,纤维黄色瘤密度较低。纤维肉瘤及恶性纤维组织细胞瘤少数发生淋巴结转移及直接浸润     

经颈静脉肝内门体静脉内支架分流术术式改良的实验研究

目的：探讨建立改良式猪经颈静脉肝内门体静脉内支架分流术（TIPSS）模型的可行性及其意义。方法：11只家猪分成2组，7只采用改良术式（经肝段下腔静脉穿刺门脉）建立TIPSS模型，另4只行常规TIPSS作对照。共置入4枚进口覆膜镍钛合金支架，8枚国产覆聚氨酯膜支架。其中，改良组7只猪置入7枚支架（4枚进口支架，3枚国产支架）；对照组4只猪置入5枚国产覆膜支架（1只猪置入时支架发生移位，故加用1枚支架）。术后4周（5只），8周（2只）和12周（4只）进行门脉造影观察分流道通畅情况。动物处死后，行分流道大体和组织病理学检查。结果：术后4周，改良组2只分流道通畅（进口支架、国产支架各1枚），分流道表面均形成完整的假性内膜组织；另5只分流道在4至12周均闭塞，分流道内形成血栓，其中2只内支架伸入下腔静脉内不全，陷入肝实质内。常规组4只分流道在4、8和12周观察期内均闭塞。两组间分流道肝（下腔）静脉端，肝实质段和门静脉端各段的增生组织厚度对比差异均无显著性意义（t值分别为0．14、0．16和0．20，P值均＞0．05）。结论：改良式猪TIPSS模型的建立是安全和可行的。改良式TIPSS中应采用覆膜支架，并应有足够长度伸入至两端静脉内，有助于防止增生组织向分流道内长入。     

F形双腔管的制作及其在体外架桥胆汁回流术中的应用

1985年以来，作者设计制作了F形双腔管，应用于重症胆管疾病52例。经临床观察证明，此管既能回收胆汁，又可通过其内管注药液及高营养流食或补液，且无并发症，效果满意。一、制作方法取2条22～24号T形管，一条作胆总管部引流；另一条剪去长轴管（保留5cm），取长4cm，直径0．3cm玻璃管2个，用于T形管与F形双腔管的联接；取18号注射针头一个，磨去针锋插入长47cm，内经0．2cm的硅胶管作内管；取长30cm，直径0．4cm硅胶管一根作为空肠造瘘输入管。将以上材料连接起来（附图），即成为F形双腔管。二、应用方法1．连接方法：将F形管在1％新…     

骨髓基质细胞移植联合应用脑源性神经营养因子促进大鼠脊髓损伤修复

1材料与方法 取Wistar大鼠（鼠龄2～4个月）股骨和胫骨骨髓组织，采用Percoll分离液（比重1．077）分离法获取骨髓基质细胞（BMSCs）进行培养纯化。细胞传3代，移植前72h按20μmol／L终浓度加入5溴-2脱氧尿嘧啶（BrdU）标记细胞核。采用大鼠T12．13脊髓半横断损伤模型。选择Wistar大鼠48只，体重250～300g，雌雄不拘。随机分成Ⅰ组：脊髓半横断后明胶内给予DMEM10μl；Ⅱ组：明胶内给予脑源性神经营养因子（BDNF）10μl（33μg／m1）。     

γ射线对小鼠主动脉性腺中肾区基质细胞氨基肽酶N/CD13活性的影响

目的探讨小鼠主动脉性腺中肾（AGM）区基质细胞氨基肽酶N／CD13（APN／CD13）的表达和放射损伤前后该酶活性的变化及意义。方法采用免疫组织化学染色、RT-PCR检测AGM区基质细胞APN／CD13的表达；^60Coγ射线8．0Gy照射细胞，在不同的时间点用分光光度计检测APN／CD13的酶活性。结果AGM区基质细胞APN／CD13呈强阳性表达；放射损伤后酶活性呈一过性降低，继而升高，4h达高峰，24—48h基本恢复至照射前水平。结论APN／CD13在AGM区基质细胞上呈强阳性表达；在放射损伤后酶活性增高，可能是促进造血功能恢复的一种代偿机制。     

生物可降解性血管内支架的制备及其性能研究

目的 对采用聚左旋乳酸(PLLA)制备生物可降解性血管内支架(BIS)进行研究，并评估其物理学、机械力学性能及其生物相容性?方法先采用分子量为100 000 U的PLLA制作支架基杆，继而对支架基杆造孔和涂膜。支架固化成形后，对其主要的物理学和机械力学特性进行测试，并将22枚Z形BIS置入11只实验犬的腹主动脉和髂动脉内，分期处死动物行病理学观察。结果 制备出螺旋形和Z形2种型号支架，基杆直径为0．1～0．6mm，支架扩张后直径为6～15mm、长度为30～80mm；支架径向支持力为1．6～2．0kPa(1kPa=7．5mm Hg)、扩张率(压缩后支架直径与释放后完全展开支架直径的比值)为6．0～6．5，短缩率小于8％～10％，表面积与扩张后表面积的比值为0．16～0．18(小于0．2)，此种支架X线显示性差，透视下看不到。支架置入后1周，显微镜下可见支架杆部有少许纤维组织和少量血小板沉着；4周，支架杆部大部分被新生内膜覆盖；8周时支架被内膜完全覆盖，未见明显内膜增生，管壁光整，管腔通畅。图像分析显示8周后内膜生长趋势减弱。结论 此种BIS的物理学和机械力学特性可满足支架血管内置入的要求，特别是Z形BIS更适合于置入、释放：置入动物血管后的早期，支架可引起轻度炎性反应；8周时，支架被内膜完全覆盖；8周后未见显著的内膜增生性改变。具有可靠的机械强度和良好的生物相容性。     

止血用ZSM-5沸石的细胞毒性评价

目的：对ZSM-5沸石进行细胞毒性评价，探讨其作为急救止血材料的安全性。方法：参照我国医疗器械生物学评价标准：①采用L929细胞经沸石浸提液培养后，MTT法测定其相对增值率；②将L929细胞与沸石直接接触培养，不同时间观察细胞生长状态及细胞计数；③将L929细胞种植于沸石表面，扫描电镜观察其生长情况。结果：ZSM-5沸石性质稳定，细胞毒性程度为0～1级，符合我国医疗器械生物学评价标准。L929细胞与沸石直接接触培养生长良好，形态学无明显改变。结论：ZSM-5沸石细胞相容性好，符合我国医疗器械生物学评价标准。     

以京尼平交联制备新型人工神经支架材料及其生物学特性的对比研究

目的 从超微结构、孔隙率、溶胀率、降解率、交联度及细胞毒性等方面分别比较紫外线、京尼平及戊二醛交联后的壳聚糖复合Ⅰ型胶原蛋白人工神经支架材料的生物学特性. 方法 (1)材料按交联方法不同分为三组:紫外线组、京尼平组、戊二醛组.(2)经扫描电镜观察三组材料内部结构的排列规律及走形,测量其孔径大小、计算孔隙率及孔径分布等指标.(3)溶胀率与体外降解率:三组材料交联完后立即称重(W_0),然后在培养皿中加入10 ml无菌PBS,24 h后用无菌滤纸擦干水分称重(W_1).溶胀率(%)=(W_1-W_0)/W_0×100%.剩余材料于4,8,12周分别取出后称重(W_2).降解率(%)=(W_1-W_2)/W_1×100%.(4)检测交联度:每组取10根材料,其中5根加入碳酸氢钠和三硝基苯磺酸(TNBS),再加盐酸,在346 nm测吸光度(A)值(A_(三硝基苯磺酸)).另外5根先加盐酸,然后再加TNBS,其余步骤相同,测得吸光度取平均值作为对照(A_对),交联后吸光度值为:A_(交联后)=A_(三硝基苯磺酸)-A_(对).再取一组10根未交联过的材料,以同样步骤测吸光度,得到交联前吸光度(A_(交联前)).交联度=(A_(交联前)-A_(交联后))/A_(交联前)×100%.(5)细胞毒性试验:遵照GB/T16886/ISO 10993医疗器械生物学评价之体外细胞毒性试验原则,采用国际标准的两种试验方法,选用建系的L929小鼠成纤维细胞对改性后的支架材料进行体外细胞毒性试验. 结果 (1)未交联的材料为均匀圆柱状,内部为孔径均匀且平行排列的微观结构,其微孔直径为30～120 μm;交联后紫外线组孔径基本不变,京尼平、戊二醛两组孔径均变小.(2)京尼平和戊二醛组孔隙率差异无统计学意义,两者都要高于紫外线组;而溶胀率京尼平组高于戊二醛组,戊二醛组又高于紫外线组.(3)京尼平和戊二醛两组的交联度分别为55.3%和82.5%.(4)京尼平和戊二醛组在PBS中浸泡4,8,12周,体外降解率差异无统计学意义;而紫外线组材料降解明显高于前两者.(5)戊二醛组浸提液培养的细胞出现部分坏死现象,相反京尼平和紫外线组细胞生长良好. 结论 以京尼平交联壳聚糖复合Ⅰ型胶原蛋白制备出改进的人工神经支架,具有良好的生物稳定性和生物相容性,为神经组织工程领域提供了一种具有应用潜力的材料.     

半月板纤维软骨细胞与壳聚糖/聚磷酸钙体外复合培养的实验研究

目的:观察半月板纤维软骨细胞在不同配比壳聚糖/聚磷酸钙(chitosan/calciumpolyphosphate,CS/CPP)支架材料上的生长状况,优选最佳配比CS/CPP生物材料作为组织工程半月板支架材料。方法:采用机械分离与酶连续消化相结合的方法体外分离兔半月板纤维软骨细胞,单层培养传代至第3代,并对其进行表型鉴定。采用共混-化学交联固化-冷冻干燥法将CS、醛基化海藻酸钠(aldehyde alginate,ADA)、CPP有机地结合起来,制备4种不同配比的新型组织工程半月板复合支架材料。将体外分离培养的第3代半月板细胞,通过二次沉淀接种法将其种植于不同配比的CS/CPP支架上,体外培养7天,采用相差倒置显微镜、SEM、HE染色观察细胞在支架上的形态、黏附、生长情况。结果:体外分离培养的第3代半月板细胞基本维持纤维软骨细胞的表型。相差倒置显微镜下可见,细胞在支架上黏附良好;扫描电镜下可见,细胞在支架上均匀分布,细胞多数呈多角形,并有基质分泌;HE染色结果显示,有细胞长入到三维支架材料内部。其中,半月板细胞在3:7的CS/CPP支架材料上单位面积内数目最多,生长最旺盛,细胞外基质分泌最多。结论:三维多孔的CS/CPP复合材料能促进半月板纤维软骨细胞的黏附、生长和增殖,其中3:7的CS/CPP支架材料细胞相容性和生物活性最好,最适于半月板纤维软骨细胞粘附和生长,并且能促进半月板细胞增殖和维持其表型,有望成为组织工程半月板良好的支架载体。     

骨修复材料多孔聚磷酸钙的制备及细胞相容性研究

目的 为了解决骨组织工程中成骨细胞在可降解支架材料上三维生长这一问题,本文对无机聚合物聚磷酸钙（CPP）生物陶瓷进行了研究.方法 实验制备出CPP多孔材料,并以羟基磷灰石,磷酸三钙作为对照材料,检测了材料的细胞毒性,并与成骨细胞进行复合生长.结果 表明聚磷酸钙不仅无细胞毒性,而且能促进成骨细胞的生长,与成骨细胞复合后,细胞能在材料中三维生长,并能分泌出细胞外基质,因此具有良好的细胞相容性.结论 多孔聚磷酸钙能促进成骨细胞生长,并为细胞良好生长提供三维空间环境,同时本实验也为可降解无机聚合物作为骨组织工程支架材料的研究提供了新的思路.     

Micro-imaging of implanted scaffolds using combined MRI and micro-CT

Rationale and objectivesThanks to the advanced studies in biomaterial engineering a panoply of polymers can be used to manufacture porous scaffolds for bone tissue regeneration. Suitability of the scaffold for its purpose is determined by factors like size of the pores, its orientation and shape, as well as biocompatibility of the material. Even though a variety of analysis methods is available for in vitro studies, investigating the process of bone reconstruction on implanted scaffold meets with difficulties.Methods and materialsPolylactide porous sponges imbued in hydroxyapatite were implanted into long bones of white New Zealand rabbits for 3 months. The bones obtained from the animals were subjected to MRI and μCT imaging. The obtained images were subsequently fused together.Results and conclusionsCombined MRI and μCT resulted in high resolution diagnostic images which allow for: implant positioning, inflammation divulgement, rating degree of implant resorption, observation of newly formed trabeculae, texture analysis and other quantitative measurements.     

Culture of human bone marrow-derived mesenchymal stem cells on of poly(l-lactic acid) scaffolds: potential application for the tissue engineering of cartilage

Purpose

Due to the attractive properties of poly(l-lactic acid) (PLLA) for tissue engineering, the aim was to determine the growth and differentiation capacity of mesenchymal stromal cells (MSCs) in PLLA scaffolds and their potential use in the treatment of cartilage diseases.

Methods

MSCs were cultured in PLLA films and thin porous membranes to study adherence and proliferation. Permeability and porosity were determined for the different scaffolds employed. The optimal conditions for cell seeding were first determined, as well as cell density and distribution inside the PLLA. Scaffolds were then maintained in expansion or chondrogenic differentiation media for 21 days. Apoptosis, proliferation and chondrogenic differentiation was assessed after 21 days in culture by immunohistochemistry. Mechanical characteristics of scaffolds were determined before and after cell seeding.

Results

MSCs uniformly adhered to PLLA films as well as to porous membranes. Proliferation was detected only in monolayers of pure PLLA, but was no longer detected after 10 days. Mechanical characterization of PLLA scaffolds showed differences in the apparent compression elastic modulus for the two sizes used. After determining high efficiencies of seeding, the production of extracellular matrix (ECM) was determined and contained aggrecan and collagens type I and X. ECM produced by the cells induced a twofold increase in the apparent elastic modulus of the composite.

Conclusions

Biocompatible PLLA scaffolds have been developed that can be efficiently loaded with MSCs. The scaffold supports chondrogenic differentiation and ECM deposition that improves the mechanics of the scaffold. Although this improvement does not met the expectations of a hyaline-like cartilage ECM, in part due to the lack of a mechanical stimulation, their potential use in the treatment of cartilage pathologies encourages to improve the mechanical component.     

A novel nano-structured porous polycaprolactone scaffold improves hyaline cartilage repair in a rabbit model compared to a collagen type I/III scaffold: in vitro and in vivo studies

Purpose

To develop a nano-structured porous polycaprolactone (NSP-PCL) scaffold and compare the articular cartilage repair potential with that of a commercially available collagen type I/III (Chondro-Gide^®) scaffold.

Methods

By combining rapid prototyping and thermally induced phase separation, the NSP-PCL scaffold was produced for matrix-assisted autologous chondrocyte implantation. Lyophilizing a water–dioxane–PCL solution created micro and nano-pores. In vitro: The scaffolds were seeded with rabbit chondrocytes and cultured in hypoxia for 6 days. qRT–PCR was performed using primers for sox9, aggrecan, collagen type 1 and 2. In vivo: 15 New Zealand White Rabbits received bilateral osteochondral defects in the femoral intercondylar grooves. Autologous chondrocytes were harvested 4 weeks prior to surgery. There were 3 treatment groups: (1) NSP-PCL scaffold without cells. (2) The Chondro-Gide^® scaffold with autologous chondrocytes and (3) NSP-PCL scaffold with autologous chondrocytes. Observation period was 13 weeks. Histological evaluation was made using the O’Driscoll score.

Results

In vitro: The expressions of sox9 and aggrecan were higher in the NSP-PCL scaffold, while expression of collagen 1 was lower compared to the Chondro-Gide^® scaffold. In vivo: Both NSP-PCL scaffolds with and without cells scored significantly higher than the Chondro-Gide^® scaffold when looking at the structural integrity and the surface regularity of the repair tissue. No differences were found between the NSP-PCL scaffold with and without cells.

Conclusion

The NSP-PCL scaffold demonstrated higher in vitro expression of chondrogenic markers and had higher in vivo histological scores compared to the Chondro-Gide^® scaffold. The improved chondrocytic differentiation can potentially produce more hyaline cartilage during clinical cartilage repair. It appears to be a suitable cell-free implant for hyaline cartilage repair and could provide a less costly and more effective treatment option than the Chondro-Gide^® scaffold with cells.     

关节软骨修复细胞基因治疗中软骨细胞支架载体特点

目的 探讨四种不同类型三维支架中培养的关节软骨细胞活性状况及其转基因特性.方法 原代培养兔膝关节软骨细胞,并且以表达绿色荧光蛋白(GFP)和萤火虫荧光素酶(GL3)的腺病毒载体AdGFP和AdGL3进行感染.在I型胶原海绵、纤维蛋白胶、透明质酸和聚乳酸四种类型的支架材料中,以荧光显微镜和荧光素酶分析法检测细胞的活性状况及其转基因特性;以阿辛蓝染色评价软骨基质的产生.结果 表达绿色荧光蛋白的腺病毒(AdGFP)成功感染兔关节软骨细胞,并且持续表达绿色荧光蛋白.被感染的软骨细胞在所有被测试的细胞支架上均能存活,并能表达GFP和荧光素酶报告基因.与其余三种支架比较,聚乳酸支架中转基凶表达率最高(P<0.01).而且聚乳酸培养体系中,4周时可以检测到阿辛蓝染色阳性的基质材料.结论 在关节软骨修复的细胞基因治疗领域,聚乳酸可能是一种合适的支架材料.     

定向结构组织工程软骨支架的构建

目的基于仿生学原理,构建类似软骨真实结构的定向结构组织工程软骨支架,以解决目前组织工程软骨修复过程中存在的支架亲水性相容性不够的缺陷以及新生软骨生理功能和机械性能不能长期维持等问题。方法选择软骨基质及壳聚糖共混溶液基于定向结晶及热致相分离工艺构建定向结构支架,研究支架孔径及力学性能生物相容性、细胞生长情况等。结果材料配比、模具底端温度等是影响着定向结构支架的孔径及力学性能的主要因素,定向结构支架轴向力学性能优于垂直轴向,细胞大量贴附支架表面,并沿着定向孔隙生长。结论采用上述方法构建的支架孔径可控,轴向抗压性能好,生物相容性,亲水性好,并有利于软骨细胞沿支架定向孔隙排布。     

One-step osteochondral repair with cartilage fragments in a composite scaffold

Purpose

This study proposes a single-step therapeutic approach for osteochondral defects using autologous cartilage fragments loaded onto a scaffold composed of a hyaluronic acid (HA) derivative, human fibrin glue (FG) and autologous platelet-rich-plasma (PRP), in a rabbit model. The aim is to demonstrate the in vitro outgrowth of chondrocytes from cartilage fragments and the in vivo formation of a functional repair tissue.

Methods

In vitro: minced articular cartilage was loaded onto two different types of scaffold (paste or membrane) according to two different HA preparations (injectable HA-derivative or HA-derivative felt). In vivo: trochlear osteochondral defects were created in 50 adult rabbits, which were then assigned to 5 different treatment groups: cartilage fragments loaded onto membrane scaffolds with FG (Group 1) or without FG (Group 2); membrane scaffolds alone with FG (Group 3) or without FG (Group 4); empty defects (Group 5). Membrane scaffolds were used “in vivo” for simpler preparation and better adhesive properties. Repair processes were evaluated histologically and by immunohistochemistry at 1, 3, and 6 months.

Results

An in vitro time-dependent cell outgrowth from cartilage fragments was observed with both types of scaffolds. At 6 months, in vivo, cartilage fragment-loaded scaffolds induced significantly better repair tissue than the scaffold alone using histological scoring. Repair in Group 2 was superior to that in any of the control groups (p < 0.05).

Conclusion

Autologous cartilage fragments loaded onto an HA felt/FG/PRP-scaffold provided an efficient cell source, and allowed for an improvement of the repair process of ostechondral defects in a rabbit model. Human FG, however, hampered the rabbit healing process. These results may have clinical relevance as they show the potential of a novel one-stage repair technique for osteochondral defects.     

多孔聚乳酸-聚乙醇酸共聚物作为缓释重组人骨形态发生蛋白-2载体的实验研究

目的 探讨多孔聚乳酸-聚乙醇酸共聚物(PLGA)作为重组人骨形态发生蛋白-2(rhBMP-2)的载体，通过体外释放试验和体内活性试验来评价rhBMP-2释放的动力学过程及活性。方法 采用乳液冷冻干燥法制作含rhBMP-2缓释系统的PLGA支架，支架进行扫描电镜观察；采用高效液相色谱分析仪检测不同时间点释放液中rhBMP-2的含量，进行累积释放量的动态观察；将缓释rhBMP-2支架植入SD大鼠大腿股部肌袋内，分别在不同时间点进行组织学观察。结果 支架材料的形态学观察显示，材料表面呈多孔状；rhBMP-2从支架中释放的动力学过程为第1天表现为爆发性释放(30.0％)，以后缓慢持续释放，至1个月左右释放量达80.6％；活性评价结果显示，rhBMP-2缓释支架组可见新生骨组织形成伴较多的骨母细胞排列，无rhBMP-2支架组则无成骨现象。结论 多孔PLGA可作为rhBMP-2的缓释载体，并具有良好的生物活性，可作为骨组织工程研究中的新型支架，同时具有临床应用的可行性。     

Real-time in vivo monitoring of viable stem cells implanted on biocompatible scaffolds

Purpose  Three-dimensional fibrous scaffolds provide an environment that enhances transplanted stem cell survival in vivo and facilitates imaging their localization, viability, and growth in vivo. To assess transplanted stem cell viability on biocompatible polymer scaffolds in vivo, we developed in vivo imaging systems for evaluation of implanted viable neural stem cells (NSC) and mesenchymal stem cells (MSC) on scaffolds using luciferase or sodium/iodide symporter (NIS) genes. Methods  Firefly luciferase stably expressing-C6 cell was established (C6-Fluc). The human neural stem cell, F3, was infected with adenoviral vector carrying luciferase gene (F3-Fluc) and MSC expressing NIS controlled by ubiquitin C promoter using lentiviral vector was established by treating blasticidine for 2 weeks (MSC-NIS). Chitosan and poly l-lactic acid (PLLA) scaffolds were used for in vivo image. In vivo expression of luciferase and human NIS was examined by bioluminescence image or ^99mTc-pertechnetate gamma camera image, respectively. The cell/scaffold complex was implanted into subcutaneous or abdominal area of BALB/C nude mouse. For quantitative evaluation of cell viability, regions of interest were drawn on ^99mTc-pertechnetate scintigraphy by manual. Results  The gradual increase of luciferase activity was observed in C6-Fluc seeded with chitosan according to the increase in the number of cells. C6-Fluc/chitosan complex subcutaneously implanted into nude mice showed longitudinal bioluminescence image until 34 days. Luciferase image of abdominal-injected C6-Fluc/PLLA complex was saturated in only 14 days, showing great cell growth due to abundant nutrients. F3 cells showed well-incorporated pattern with fibrous chitosan scaffold using scanning electron microscopy. F3 infected with Ad-Fluc showed >100-fold higher luciferase activity than luciferase activity in F3. Cell-number-dependent increase of luciferase activity was shown in F3-Fluc seeded on chitosan. F3-Fluc incorporation into chitosan after abdominal injection was clearly visible on bioluminescence image up to 11 days. Radionuclide imaging showed higher uptake by MSC-NIS on PLLA scaffolds than by MSC-NIS not seeded on a scaffold. Quantitative data showed significantly better survival of MSC-NIS on PLLA scaffolds than without scaffold at 72 h post-implantation, which concurred with histologic findings. Conclusion  These results suggest that NSC-Fluc and MSC-NIS cells incorporated within polymer scaffolds can be monitored on a long-term basis by serial in vivo imaging. We believe that a biocompatible scaffold-based imaging system could be used to assess stem cell viabilities in a non-invasive way to aid the development of regenerative therapeutics. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Soonhag Kim and Dong Soo Lee contributed equally to this investigation as corresponding authors and Do Won Hwang and Sung June Jang equally contributed as co-first author.