Samavedi Satyavrata, Vaidya Prasad, Gaddam Prudhvidhar, Whittington Abby R, Goldstein Aaron S
Department of Chemical Engineering, Virginia Tech, Blacksburg, VA, 24061.
Biotechnol Bioeng. 2014 Dec;111(12):2549-59. doi: 10.1002/bit.25299. Epub 2014 Sep 26.
Although bone-patellar tendon-bone (B-PT-B) autografts are the gold standard for repair of anterior cruciate ligament ruptures, they suffer from drawbacks such as donor site morbidity and limited supply. Engineered tissues modeled after B-PT-B autografts are promising alternatives because they have the potential to regenerate connective tissue and facilitate osseointegration. Towards the long-term goal of regenerating ligaments and their bony insertions, the objective of this study was to construct 2D meshes and 3D cylindrical composite scaffolds - possessing simultaneous region-wise differences in fiber orientation, diameter, chemistry and mechanical properties - by electrospinning two different polymers from off-set spinnerets. Using a dual drum collector, 2D meshes consisting of an aligned polycaprolactone (PCL) fiber region, randomly oriented poly(lactide-co-glycolide) (PLGA) fiber region and a transition region (comprised of both PCL and PLGA fibers) were prepared, and region-wise differences were confirmed by microscopy and tensile testing. Bone marrow stromal cells (BMSCs) cultured on these meshes exhibited random orientations and low aspect ratios on the random PLGA regions, and high aspect ratios and alignment on the aligned PCL regions. Next, meshes containing an aligned PCL region flanked by two transition regions and two randomly oriented PLGA regions were prepared and processed into 3D cylindrical composite scaffolds using an interpenetrating photo-crosslinkable polyethylene glycol diacrylate hydrogel to recapitulate the shape of B-PT-B autografts. Tensile testing indicated that cylindrical composites were mechanically robust, and eventually failed due to stress concentration in the aligned PCL region. In summary, this study demonstrates a process to fabricate electrospun meshes possessing region-wise differences in properties that can elicit region-dependent cell responses, and be readily processed into scaffolds with the shape of B-PT-B autografts.
尽管骨-髌腱-骨（B-PT-B）自体移植物是前交叉韧带断裂修复的金标准，但它们存在供区发病和供应有限等缺点。模仿B-PT-B自体移植物构建的工程组织是很有前景的替代物，因为它们有再生结缔组织和促进骨整合的潜力。为了实现韧带及其骨附着部位再生的长期目标，本研究的目的是通过从错位喷丝头静电纺丝两种不同的聚合物，构建二维网片和三维圆柱形复合支架，这些支架在纤维取向、直径、化学性质和力学性能方面具有区域差异。使用双鼓收集器，制备了由排列的聚己内酯（PCL）纤维区域、随机取向的聚（丙交酯-共-乙交酯）（PLGA）纤维区域和过渡区域（由PCL和PLGA纤维组成）组成的二维网片，并通过显微镜和拉伸试验确认了区域差异。在这些网片上培养的骨髓间充质干细胞（BMSC）在随机的PLGA区域表现出随机取向和低纵横比，而在排列的PCL区域表现出高纵横比和排列。接下来，制备了包含一个排列的PCL区域两侧各有两个过渡区域和两个随机取向的PLGA区域的网片，并使用互穿的可光交联聚乙二醇二丙烯酸酯水凝胶将其加工成三维圆柱形复合支架，以重现B-PT-B自体移植物的形状。拉伸试验表明，圆柱形复合材料在力学上是坚固的，最终由于排列的PCL区域的应力集中而失效。总之，本研究展示了一种制造具有区域性质差异的静电纺网片的方法，这种网片可以引发区域依赖性细胞反应，并易于加工成B-PT-B自体移植物形状的支架。
