Tissue engineering scaffolds should ideally mimic the natural ECM in structure and function. Electrospun nanofibrous scaffolds are easily fabricated and possess a biomimetic nanostructure. Scaffolds can mimic ECM function by acting as a depot for sustained release of growth factors. bFGF, an important growth factor involved in tissue repair and mesenchymal stem cell proliferation and differentiation, is a suitable candidate for sustained delivery from scaffolds. In this study, we present two types of PLGA nanofibers incorporated with bFGF, fabricated using the facile technique of blending and electrospinning (Group I) and by the more complex technique of coaxial electrospinning (Group II). bFGF was randomly dispersed in Group I and distributed as a central core within Group II nanofibers; both scaffolds showed similar protein encapsulation efficiency and release over 1-2 weeks. Although both scaffold groups favored bone marrow stem cell attachment and subsequent proliferation, cells cultured on Group I scaffolds demonstrated increased collagen production and upregulated gene expression of specific ECM proteins, indicating fibroblastic differentiation. The study shows that the electrospinning technique could be used to prolong growth factor release from scaffolds and an appropriately sustained growth factor release profile in combination with a nanofibrous substrate could positively influence stem cell behavior and fate.

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Unlike braided fabrics, knitted scaffolds have been proven to favor deposition of collagenous connective tissue matrix, which is crucial for tendon/ligament reconstruction. But cell seeding of such scaffolds often requires a gel system, which is unstable in a dynamic situation, especially in the knee joint. This study developed a novel, biodegradable nano-microfibrous polymer scaffold by electrospinning PLGA nanofibers onto a knitted PLGA scaffold in order to provide a large biomimetic surface for cell attachment. Porcine bone marrow stromal cells were seeded onto either the novel scaffolds by pipetting a cell suspension (Group I) or the knitted PLGA scaffolds by immobilizing in fibrin gel (Group II). Cell attachment at 36 hours, cell proliferation and extracellular matrix synthesis at 1 week, and mechanical properties over 2 weeks were investigated. Cell attachment was comparable and cell proliferation was faster in Group I. Moreover, cellular function was more actively exhibited in Group I, as evident by the higher expression of collagen I, decorin, and biglycan genes. Thus, this novel scaffold, facilitating cell seeding and promoting cell proliferation, function, and differentiation, could be applied with promise in tissue engineering of tendon/ligament.

Six normal cadaver lower limbs were mounted on a specially designed loading apparatus. Wires were used to simulate the five muscle bellies of the quadriceps, the ratio of their tensions having been determined from that of the anatomical cross-sectional areas of the muscles. A three-camera system was used to track the patella during knee movements from flexion to extension. The patellofemoral contact area was determined by pressure-sensitive film. The limb was loaded with and without tension on the wire which simulated the oblique part of the vastus medialis (VMO). Absence of VMO tension caused the patella to displace laterally (4.2 mm) and increased the load on the lateral patellar facet throughout the range of knee motion. When the tension on the wire simulating vastus lateralis was reduced by 40% to simulate the effect of a lateral release procedure, the abnormal kinematics caused by the absent VMO returned to normal.

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