Fabrication and Bioactivity of Peptide-Conjugated Biomaterial Tissue Engineering Constructs.

Tissue engineering combines materials engineering, cells and biochemical factors to improve, restore or replace various types of biological tissues. A nearly limitless combination of these strategies can be combined, providing a means to augment the function of a number of biological tissues such as skin tissue, neural tissue, bones, and cartilage. Compounds such as small molecule therapeutics, proteins, and even living cells have been incorporated into tissue engineering constructs to influence biological processes at the site of implantation. Peptides have been conjugated to tissue engineering constructs to circumvent limitations associated with conjugation of proteins or incorporation of cells. This review highlights various contemporary examples in which peptide conjugation is used to overcome the disadvantages associated with the inclusion of other bioactive compounds. This review covers several peptides that are commonly used in the literature as well as those that do not appear as frequently to provide a broad scope of the utility of the peptide conjugation technique for designing constructs capable of influencing the repair and regeneration of various bodily tissues. Additionally, a brief description of the construct fabrication techniques encountered in the covered examples and their advantages in various tissue engineering applications is provided.

Thread Size and Polymer Composition of 3D Printed and Electrospun Wound Dressings Affect Wound Healing Outcomes in an Excisional Wound Rat Model.

Thread size and polymer composition are critical properties to consider for achieving a positive healing outcome with a wound dressing. Three-dimensional (3D) printed scaffolds and electrospun mats both offer distinct advantages as replaceable wound dressings. This research aims to determine if the thread size and polymer compositions of the scaffolds affect skin wound healing outcomes, an aspect that has not been adequately explored. Using a modular polymer platform, four polyester direct-write 3D printed scaffolds and electrospun mats were fabricated into wound dressings. The dressings were applied to splinted, full thickness skin wounds in an excisional wound rat model and evaluated against control wounds to which no dressing was applied. Wound closure rates and reduction of the wound bed width were not affected by the thread size or polymer composition. However, epidermal thickness was larger in wounds treated with electrospun dressings and was slightly affected by the polymer composition. Two of the four tested polymer compositions lead to delayed reorganization of granulation tissues. Moreover, enhanced angiogenesis was seen in wounds treated with 3D printed dressings compared to those treated with electrospun dressings. The results from this study can be used to inform the choice of dressing architecture and polymer compositions to achieve positive wound healing outcomes.

Pendant Functionalized Polyester Nanofibers with Dual Cargo Release.

Common polymeric biomaterials lack the ability to control the release of multiple bioactive compounds due to their inherent lack of functionality. These materials often require additional components or complicated fabrication techniques to achieve the separate release profiles desired for wound healing and tissue engineering applications. This prevents many biomaterials from being translated to the clinic, because the complexity of the wound environment necessitates temporal control of multiple additives for effective healing. Electrospun nanofibers comprised of a functional polymer would allow for separate release profiles of multiple bioactive compounds through covalent conjugation or tuning noncovalent interactions. In this work, two fluorescent dyes as model drugs were released from functional polyester electrospun mats. Two mats were fabricated: one in which both dyes were blended into the electrospinning solution and one in which one dye was blended and the other was covalently conjugated to the polymer. Average fiber diameters were determined using scanning electron microscopy, while fluorescence microscopy showed the presence of both dyes in the fibers. Dye release was tracked using UV-vis spectroscopy by comparing measured values to standard curves. Finally, degradation of the mats was tracked using gel permeation chromatography. With this functional polyester platform, distinct release profiles were achieved for two model drugs. Not only does the release of two model drugs show potential for the future use of this polymer platform in the applications of wound healing and tissue engineering but also the ability to incorporate several distinct conjugation chemistries is of great benefit.