筋膜包裹的骨髓间充质干细胞/聚己内酯复合体血管化组织工程骨修复比格犬骨缺损

背景：骨组织工程技术的材料/细胞复合物已能在肌肉、皮下等异位组织内成骨,或是在小型哺乳动物的骨缺损处修复成骨,但这与临床的实际仍有较大差距,骨组织工程技术能否修复大型哺乳动物大范围的骨缺损,以及如何促进组织工程骨的体内再血管化进程还不明确。 目的：观察应用比格犬带血管蒂深筋膜瓣及组织工程骨在体内的成骨情况。 方法：分离培养比格犬骨髓间充质干细胞,将骨髓间充质干细胞以自然沉淀法进行组织构建,接种于聚己内酯材料上,与支架材料复合。在比格犬左足胫骨中段制作骨-骨膜缺损模型,植入以筋膜包裹的骨髓间充质干细胞/聚己内酯复合体作为实验组;右足制作胫骨中段骨-骨膜缺损模型后,植入骨髓间充质干细胞/聚己内酯复合体;另取2只犬制作骨-骨膜缺损模型不植入任何材料作为空白对照。术后进行大体、X射线片、组织学、磁共振灌注成像观察骨模具上成骨细胞生长与血管化情况。 结果与结论：空白对照组无新骨生成,无血管长入,最后缺损由纤维瘢痕组织填充;对照组8~16周骨缺损逐渐被骨样组织填充,可见较多的骨痂,骨痂向移植物长入,断端连接不完全,髓腔硬化。实验组成骨过程及速度明显优于对照组,术后6周骨痂量较多,术后8周支架材料已完全降解,术后12周骨缺损完全修复,可见大量松质骨形成,新骨髓腔较通畅,骨皮质连续较牢靠,所形成的血管在数量、孔径和发布上均明显优于对照组。提示组织工程骨有较强、较快修复大动物大段负重骨缺损的能力,而带蒂的筋膜瓣则通过促进其再血管化而使其这种能力得到更好的发挥。     

明胶/聚己内酯纳米纤维电纺膜在组织工程中的应用进展

天然高分子材料明胶(Gelatin,GT)和人工合成高分子材料聚己内酯(Polycaprolactone,PCL),两者都具有良好的生物相容性和可降解性,已被应用于组织工程研究领域。然而,单一组分的GT和PCL材料存在诸多缺点。GT/PCL复合材料克服了单一组分支架存在的缺点,具有理化性能佳和组分优势互补等特点,可应用于构建组织工程器官和修复组织损伤。本文对GT/PCL纳米纤维电纺膜的特征及其在组织工程多个领域中的应用研究现状进行系统性回顾。     

Immobilization of cross‐linked lipase aggregates onto magnetic beads for enzymatic degradation of polycaprolactone

Candida rugosa lipase was immobilized on amino‐functionalized magnetic supports via cross‐linked enzyme aggregates (CLEA) and used to enhance the enzymatic degradation of polycaprolactone (PCL). The maximum amounts of lipase immobilized on the magnetic beads using glutaraldehyde as a coupling agent were determined to be 33.7 mg/g of beads with an 81% recovery of activity after immobilization. Compared to the free enzyme, the immobilized lipase showed the optimum pH at 1 unit higher (pH 8.0) and also retained its enzymatic activity at higher temperatures. There was 62.9% retention of lipase activity after 30 consecutive reuses, indicating its stability and reusability in aqueous media. Moreover, the immobilized lipase maintained more than 80% of its initial activity during 30 days storage period, while the free lipase lost all under same condition. In addition, the immobilized lipase showed a more than 6‐fold increase in biodegradability over the free lipase when the immobilized lipase was used to degrade PCL in a batch system. Higher thermal and storage stability, as well as good durability after repeated use of the immobilized lipase CLEA, highlights its potential applicability as large scale continuous systems for the enzymatic degradation of PCL. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Biorelevant mesoporous silicon / polymer composites: directed assembly, disassembly, and controlled release

We describe in this account a general, yet facile strategy for the directed assembly of bioactive composite materials comprised of an erodible organic polymer such as polycaprolactone and physiologically-resorbable inorganic mesoporous silicon. This method exploits a combination of capillary forces and selective interfacial coupling chemistry to produce isolable macroscale (mm sized) structures possessing a diverse range of geometries through simple mixing rather than intricate molding processes. Furthermore, we demonstrate the ability of such constructs to dissociate into their individual building blocks, with the concomitant release of embedded model compounds in a sustained manner.     

Stabilization of multiple rib fractures in a canine model

Background

Operative stabilization is frequently used in the clinical treatment of multiple rib fractures (MRF); however, no ideal material exists for use in this fixation. This study investigates a newly developed biodegradable plate system for the stabilization of MRF.

Methods

Silk fiber-reinforced polycaprolactone (SF/PCL) plates were developed for rib fracture stabilization and studied using a canine flail chest model. Adult mongrel dogs were divided into three groups: one group received the SF/PCL plates, one group received standard clinical steel plates, and the final group did not undergo operative fracture stabilization (n = 6 for each group). Radiographic, mechanical, and histologic examination was performed to evaluate the effectiveness of the biodegradable material for the stabilization of the rib fractures.

Results

No nonunion and no infections were found when using SF-PCL plates. The fracture sites collapsed in the untreated control group, leading to obvious chest wall deformity not encountered in the two groups that underwent operative stabilization.

Conclusions

Our experimental study shows that the SF/PCL plate has the biocompatibility and mechanical strength suitable for fixation of MRF and is potentially ideal for the treatment of these injuries.     

可降解生物材料人工胸壁重建犬胸壁缺损的实验研究

目的采用甲壳素短纤维增强聚己内酯(PCL)制备的人工胸壁,构建犬胸壁缺损与重建动物模型,探讨可降解生物材料人工胸壁重建胸壁缺损的可行性。方法实验犬8只,建立面积10cm×10cm的犬胸壁缺损动物模型,用甲壳素短纤维增强PCL板修复胸壁骨性缺损,通过X线、胸部CT及组织学动态观察人工胸壁的植入状况及胸壁组织的再生过程。结果所有实验犬无手术死亡和围手术期死亡,无胸壁塌陷及反常呼吸,无感染,无严重并发症。人工胸壁材料与周围胸壁肋骨及肌肉组织结合好,界面良好,固定牢靠。术后6个月甲壳素短纤维增强PCL板被纤维组织包裹。结论甲壳素纤维增强聚己内酯复合材料具有良好的生物相容性、可降解性和适宜的力学强度,能够对胸壁提供有效的支撑作用,易塑形和任意修剪,可透过X线,是一种很有前景的胸壁缺损修复材料。     

Long-Term Evaluation of Allogenic Chondrocyte-Loaded PVA–PCL IPN Scaffolds for Articular Cartilage Repair in Rabbits

ObjectiveThis study tested the long-term efficacy of two synthetic scaffolds for osteochondral defects and compare the outcomes with that of an established technique that uses monolayer cultured chondrocytes in a rabbit model.MethodsArticular cartilage defect was created in both knees of 18 rabbits and divided into three groups of six in each. The defects in first group receiving cells loaded on Scaffold A (polyvinyl alcohol–polycaprolactone semi-interpenetrating polymer network (Monophasic, PVA–PCL semi-IPN), the second on Scaffold B (biphasic, PVA–PCL incorporated with bioglass as the lower layer), and the third group received chondrocytes alone. One animal from each group was sacrificed at 2 months and the rest at 1 year. O’Driscoll’s score measured the quality of cartilage repair.ResultsThe histological outcome had good scores (22, 20, and 19) for all three groups at 2 months. At 1-year follow-up, the chondrocyte alone group had the best scores (mean 20.0 ± 1.4), while the group treated by PVA–PCL semi-IPN scaffolds fared better (mean 15 ± 4.2) than the group that received biphasic scaffolds (mean 11.8 ± 5.9). In all three groups, defects treated without cells scored less than the transplant.ConclusionThese results indicate that while these scaffolds with chondrocytes perform well initially, their late outcome is disappointing. We propose that for all scaffold-based tissue repairs, a long-term evaluation should be mandatory. The slow degrading scaffolds need further modifications to improve the milieu for long-term growth of chondrocytes and their hyaline phenotype for the better incorporation of tissue-engineered constructs.     

The effect of a hydroxyapatite impregnated PCL membrane in rat subcritical calvarial bone defects

ObjectiveThe present study evaluated the effect of polymeric-nanofibers membranes impregnated with microparticulate hydroxyapatite (HA) in the subcritical calvarial bone defects (SCBD) healing.DesignPCL membranes with and without HA were obtained by electrospinning. SCBD were perforated (3.3 mm) in left and right sides of 36 rat calvarias. The right-side SBCD of 18 animals was filled with HA mixed with blood clot and blood clot at the contralateral side. The remaining animals received PCL + HA membrane at the right-side SCBD and PCL membrane at the contralateral side. Animals were killed after 30, 60 and 90 days after surgery. Bone defect volume (in mm³) was measured by tomography (CBCT). Qualitative histological analysis and SBCD area (in mm²) were measured. Quantitative data were submitted to Kruskal-Wallis/Dunn tests.ResultsReduction of SBCD volume was observed in all treatments but PCL. Association with HA significantly improved bone healing induced by PCL and blood clot. PCL + HA induced the lowest SBCD volume at 60 and 90 days. Complete bone healing was not observed even at 90 days in SCBD treated with blood clot. In every period, more bone formation was observed for SCBD treated with membranes.ConclusionsWe concluded that both PCL membrane and HA were able to improve bone healing.     

静电纺聚己内酯/壳聚糖纳米纤维膜诱导骨髓间充质细胞成骨分化的研究

目的：观察静电纺聚己内酯/壳聚糖纳米纤维膜对骨髓间充质细胞（BMSCs）粘附、增殖和成骨分化的影响。方法：通过静电纺丝技术制备聚己内酯/壳聚糖纳米纤维膜,将第4代BMSCs接种于纤维膜,扫描电镜、碱性磷酸酶（ALP）和茜素红染色、MTT检测BMSCs粘附、分化及增殖能力。结果：在静电纺丝技术制备的聚己内酯/壳聚糖纳米纤维膜表面,BMSCs的黏附和增殖增强,呈现明显升高的ALP活性,并形成矿化结节,提示具有向成骨细胞方向分化的倾向。结论：静电纺聚己内酯/壳聚糖纳米纤维膜对BMSCs的细胞相容性较好,适合BMSCs的黏附生长,具有诱导其向成骨细胞分化的潜能,有望成为一种新型牙周组织工程支架材料。