Research in Engineering and Aviation

A preliminary evaluation of lyophilized gelatin sponges enhanced with platelet-rich plasma, hydroxyapatite, and chitin whiskers for bone regeneration

March 2013

Author(s): Sell, S.A., Rodriguez, I.A., McCool, J.M., Saxena, G., Spence, A.J., and G.L. Bowlin

Poster presentation at the 17th Annual International Workshop on Tissue Engineering, Hilton Head, SC, March 19-23, 2013.

Abstract

Healthy bone has the unique ability to spontaneously regenerate; however, if the damaged area exceeds a critical volume, bone grafting is required to complete repair. Commonly utilized options to supplement bone regeneration include autografts (patient bone), allografts (human cadaveric bone), xenografts (animal bone), and synthetic biomaterials (i.e. ceramics, cements, glasses, metals, polymers, and composites). Collagen and hydroxyapatite (HA) are popular materials when investigating bone scaffolds as their composites do an adequate job of mimicking the extracellular matrix (ECM) of natural bone. More recently, gelatin (denatured collagen) has been used as a replacement for collagen since it is less expensive, easier to obtain, and contains similar functional groups which enhance cellular response. Freeze-dried gelatin sponges have many advantages because they can be designed to fit any size defect/injury site, have the ability to swell and fill a void space, degrade controllably in a range of rates (due to various cross-linking methods) to ensure drug release and mechanical stability, and can be easily modified by incorporating various osteoconductive/osteoinductive materials (i.e. minerals, growth factors, proteins, etc.).

The purpose of this study was to perform a number of preliminary in vitro evaluations on an array of enhanced gelatin gel sponge scaffolds for use in bone regeneration. The gelatin gels were modified through the addition of a number of components which each possess unique properties conducive to the creation and regeneration of bone: a preparation rich in growth factors (PRGF, a bioactive, lyophilized form of platelet-rich plasma), HA, and chitin whiskers (CW). Platelet-rich plasma therapy is an emerging practice that has proven effective in a number of clinical applications, including enhancing bone repair through improved deposition of new bony matrix and angiogenesis. As such, the inclusion of PRGF in our gelatin scaffolds was intended to significantly enhance scaffold bioactivity, while the addition of HA and CW were anticipated to increase scaffold strength.

It was determined that a lyophilized gelatin gel sponge, modified through the addition of PRGF, HA, and CW, demonstrated clear osteogenic potential when cultured with an MG-63 osteoblast-like cell line. These scaffolds, further modified through EDC cross-linking during gelation, were able to remain intact after 90 days in culture while exhibiting a controlled protein release throughout. The lyophilized gelatin gel sponges exhibited the potential to absorb several times their weight in water and were capable of eliciting cell infiltration into the structures while promoting the formation of cell-created mineral matrix. Further testing must be performed to more accurately determine the cellular interaction with these scaffolds, in particular the cellular response inside the structures.