Scaffolds tissue engineering

A three-dimensional scaffold permits the in vitro cultivation of cell—polymer constructs that can be readily manipulated, shaped, and fixed to the defect site [26].

The matrix acts as the translator between the local environment (either in vitro or in vivo) and the developing tissue, aiding in the development of biologically viable functional tissue. However, during the 1960s to the early 1980s, the use of virgin silk negatively impacted the general acceptance of this biomaterial from the surgical practitioner perspective, e.g., the reaction of silk to the host tissue and the inflammatory potential of silk. Recently, silk matrices are being rediscovered and reconsidered as potentially useful biomaterials for a range of applications in clinical repairs and in vitro as scaffolds for tissue engineering.

Silk, as a protein, is susceptible to proteolytic degradation in vivo and over a longer period of time in vivo will slowly be absorbed. Degradation rates mainly depend on the health and physiological status of the patient, the mechanical environment of the implantation site, and the types and dimensions of the silk fibers. The slow rate of degradation of silk in vitro and in vivo makes it useful in biodegradable scaffolds for slow tissue ingrowths since the biodegradable scaffolds must be able to be retained at the implantation site, including maintaining their mechanical properties and supporting the growth of cells, until the regenerated tissue is capable of fulfilling its desired functions. The degradation rate should be matched with the rate of neotissue formation so as not to compromise the load-bearing capabilities of the tissue.

Additionally, scaffold structures, including the size and connective of pores, determine the transport of nutrients, metabolites, and regulatory molecules to and from cells. The matrix must support cell attachment, spreading, growth, and differentiation. Meinel et al. [26] concentrated on cartilage tissue engineering with the use of silk protein scaffolds and the authors identified and reported that silk scaffolds are particularly suitable for tissue engineering of cartilage starting from human mesenchymal stem cells (hMSC), which are derived from bone marrow, mainly due to their high porosity, slow degradation, and structural integrity.

Recent research with silk has focused on the development of a wire rope matrix for the development of autologous tissue-engineered anterior cruciate ligaments (ACL) using a patient’s own adult stem cells [27]. Silk fibroin offers versatility in matrix scaffold design for a number of tissue engineering needs in which mechanical performance and biological interactions are major factors for success, including bone, ligaments, tendons, blood vessels, and cartilage. Silk fibroin can also be processed into foams, films, fibers, and meshes.

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