Tissue Engineering Muscle By Micropatterning For Therapeutic Transplantation

Tissue Engineering Muscle by Micropatterning for Therapeutic Transplantation

There is growing interest to treat patients with inherited or acquired muscular disorders by transplantation of cells to the site of dysfunction to restore normal function. One candidate cell source is skeletal muscle, which can be harvested from surrounding tissues for cell culture before injecting into the site of dysfunction. However, this treatment may not be practical because harvesting skeletal muscle may lead to significant muscle loss and increased susceptibility to infection.

One effective way to develop the needed tissue is through tissue engineering. Tissue engineering is the development of molecules, cells, tissues, or organs to replace or support dysfunctional body parts. Myoblasts, which are muscle precursor cells, a form on stem cells found in muscle, are a promising cell source for tissue engineering because they play an active role in regenerating muscle due to injury. Normally quiescent, myoblasts respond to muscle injury by rapidly proliferating and then differentiating, which results in the fusion of neighboring myoblasts into myofibers. Myoblasts can be easily cultured in vitro and are capable of forming muscle. Since myoblasts have the potential to differentiate into muscle fibers, they show tremendous promise for developing muscle tissue that can be used to for cell transplantation and tissue engineering. By creating an effective means of engineering muscle tissue, clinicians can produce the needed muscle and implant it as required at the site of dysfunction.

The potential of such techniques would warrant the raising of such questions as to why such practices are not occurring regularly and why people today are still suffering from various muscle disorders. The unfortunate truth remains that engineering muscle with structural capabilities as natural muscle is still quite challenging. In vivo, muscle consists of bundles of myotube muscle fibers, which are fused multi-nucleated cells, and these muscle fibers contract synchronously. However, when myoblasts are grown in Petri dishes in vitro, they grow and differentiate into multi-nucleated myofibers in random alignment, which do not resemble natural muscle structure.

Fortunately, recent research has lent forth a couple methods in an attempt to overcome these structural impairments. One of such potential methods is to regulate cell alignment by micropatterning techniques such as microfluidic and micromolding patterning. Microfluidic patterning makes use of a silicone wafer etched by photoresist to create channels of specific widths. An inverse pattern to the wafer can be prepared using an elastic material known as poly dimethyl siloxane (PDMS),which can then be placed onto a glass substrate, through which a polymer solution can be microfluidically introduced. Once the polymer solution is allowed to evaporate, the PDMS stamp can be removed, leaving polymer channels formed on the glass surface. Similar to microfluidic patterning, micromolding uses the PDMS stamp as a mold for the polymer solution, which when dried, forms a thin film with patterned grooves.

Micropatterning has been used to effectively pattern myoblasts on silica surfaces, but myotube formation on micropatterned biodegradable polymer films has yet to be investigated. Therefore, the purpose of the project is to engineer muscle fibers in vitro, which can be applied for therapeutic implantation. By culturing myoblasts on patterned and non-patterned biodegradable substrates, it is possible that the patterned substrate will enhance cell alignment and differentiation into myofibers.

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