Meniscal Tissue Repair with Nanofibers: Future Perspectives

Abstract

The knee menisci are critical to the long-term health of the knee joint. Because of the high incidence of injury and degeneration, replacing damaged or lost meniscal tissue is extremely clinically relevant. The multiscale architecture of the meniscus results in unique biomechanical properties. Nanofibrous scaffolds are extremely attractive to replicate the biochemical composition and ultrastructural features in engineered meniscus tissue. We review recent advances in electrospinning to generate nanofibrous scaffolds and the current state-of-the-art of electrospun materials for meniscal regeneration. We discuss the importance of cellular function for meniscal tissue engineering and the application of cells derived from multiple sources. We compare experimental models necessary for proof of concept and to support translation. Finally, we discuss future directions and potential for technological innovations.

Nanofiber Scaffolds by Electrospinning for Rotator Cuff Tissue Engineering

“…The process involves the application of a high voltage (tens of kilovolts) to an emitter (spinneret) containing a solution of the polymer to be electrospun. 57 Above a certain voltage threshold, electrostatic charge breaks the surface tension of the released droplet, creating a liquid flow. The released stream quickly narrows due to evaporation of the solvent, forming fibers that are attracted to a grounded or counter electrode, which is used to collect the fibers.…”

“…63,64 Finally, generating fibers in the nanoscale range can enhance cell attachment and neomatrix formation, presumably due to fact that a single cell can attach to multiple fibers, which mimics cell attachment to natural biopolymers in native ECM. 57 While the technology of electrospinning has been developed over several decades, its potential application for general tissue engineering was first reported in 2002. 65 Since then, electrospun nanofibers have widely been tested as experimental constructs for tissue engineering research and have been proposed as scaffolds for not only the repair of tendons, 66,67 but also bone, 68 cartilage, 69 meniscus, 63 ligaments, 70 liver, 71 blood vessels, 72 nerves, 73 and for drug delivery.…”

“…The mechanical strength of integration with host tissue (scaffold-to-bone interface in most repairs and tendon-toscaffold in the bridging repair model) is also critical to assess potential for repair. 57 Several methods could help to improve tensile properties, such as the choice of polymers with higher mechanical properties, the use of cell-seeded scaffolds, 75 the use of aligned fibers, 63,77 a multilayered approach, 78 adding woven fibers, 81,98 scaling up by stacked or braided nanofiber mats, 99 or post-fabrication treatments…”

“…As shown in the studies reviewed, the assessment of tenogenic performance and potential for repair generally includes cell viability, density, proliferation and migration; expression of genes or proteins of interest; histologic and immunochemical assessment of newly formed tissue; and mechanical properties of the cell-scaffold construct. Similar to the application of nanofibrous scaffolds for meniscus tissue engineering, 57 there is, as yet, no clear consensus on a criteria to rank the performance of different cell types, scaffold materials, or culture conditions in the rotator cuff field. Furthermore, the wide variation in testing protocols and reporting of outcome measures preclude the validation and comparison of results among different studies.…”

Pneumatospinning Biomimetic Scaffolds for Meniscus Tissue Engineering

“…However, a central feature that underlies the load bearing role of meniscus is the unique organization of collagen fibers, which is an essential requirement for a functional engineered meniscus. To this end, we, and other groups, have applied electrospinning (ES) to create nanofibrous scaffolds that emulate the meniscus collagen fibrillar matrix using natural and synthetic polymer (Grogan et al, 2020;Wang et al, 2021).…”