The effect of nanofiber alignment on the maturation of engineered meniscus constructs

Abstract

The fibrocartilaginous menisci are load-bearing tissues vital to the normal functioning of the knee. Removal of damaged regions of the meniscus subsequent to injury impairs knee function and predisposes patients to osteoarthritis. In this study, we employed biodegradable nanofibrous scaffolds for the tissue engineering of the meniscus. Non-aligned (NA) or fiber-aligned (AL) nanofibrous scaffolds were seeded with meniscal fibrochondrocytes (MFCs) or mesenchymal stem cells (MSCs) to test the hypothesis that fiber-alignment would augment matrix content and organization, resulting in improved mechanical properties. Additionally, we proposed that MSCs could serve as an alternative to MFCs. With time in culture, MSC-and MFC-seeded NA and AL constructs increased in cellularity and extracellular matrix (ECM) content. Counter our initial hypothesis, NA and AL constructs contained comparable amounts of ECM, although a significantly larger increase in mechanical properties was observed for AL compared to NA constructs seeded with either cell type. Cell-seeded NA constructs increased in modulus by ~1 MPa over 10 weeks while cell-seeded AL construct increased by >7 MPa. Additionally, MSC-constructs yielded greater amounts of ECM and demonstrated comparable increases in mechanical properties, thereby confirming the utility of MSCs for meniscus tissue engineering. These results demonstrate that cell-seeded fiber aligned nanofibrous scaffolds may serve as an instructive micro-pattern for directed tissue growth, reconstituting both the form and function of the native tissue.

The Effect of Rotating Collector Design on Tensile Properties and Morphology of Electrospun Polycaprolactone Fibres

“…Musculoskletal cells, for example fibroblasts of anterior cruciate ligament in the knee, tend to orientate along fibre direction, with those positioned within parallel fibre showing enhanced proliferation [16]. Furthermore, aligned fibres support an organized neo-tissue formation that yields stronger mechanical properties [17,18].…”

“…This can be achieved by simply applying a rotating aluminium drum as the electrospinning collector. However, a very high rotation speed is required to achieve the desired alignment [16,17]. In this study, an integration of a rotating mandrel collector with gap introduction is presented.…”

Polymers to direct cell fate by controlling the microenvironment

“…The nanofibers have a diameter of 6-7.5 nm and further aggregate to higher order structures with diameters of 50 to 100 nm. Mesenchymal stem cells seeded on submicrometer electrospun poly (ε-caprolactone) meshes (C) [26]. Anisotropic skeletal myotube formation after 7 days of culture (7 d) on poly (dimethylsiloxane) substrates patterned using soft lithography (D) [15].…”

“…The goal of recent work has been to create more complex materials with defined internal architectures. To this end, composite materials and aligned fibers have been synthesized and utilized for vascular [25] and meniscal [26] tissue engineering applications, respectively. The modulus of tissues formed from aligned nanofibers can be dramatically increased as compared to unaligned fibers [26].…”

“…To this end, composite materials and aligned fibers have been synthesized and utilized for vascular [25] and meniscal [26] tissue engineering applications, respectively. The modulus of tissues formed from aligned nanofibers can be dramatically increased as compared to unaligned fibers [26]. Finally, electric fields can be utilized during the electrospinning process to create oriented polymers within the nanofibers that further recapitulate the hierarchical design found within natural anisotropic ECM [27].…”