Porcine collagen membrane for guided bone regeneration: in vitro and in vivo characterization studies

Abstract

Event Abstract Back to Event Porcine collagen membrane for guided bone regeneration: in vitro and in vivo characterization studies Natsuyo S. Lee1, Hui-Chen Chen1, Debbie Yuen1 and Shu-Tung Li1 1 Collagen Matrix, Inc., Research and Development, United States Introduction: Resorbable collagen-based membranes (RCM) have become the standard of care for guided bone regeneration (GBR) procedures. Depending on the design of the RCM, some are conformable, some have high mechanical strength, and yet some have distinct surface layers that require a direction for placement. We have developed a biomechanically strong, completely conformable single layer porcine collagen membrane (PCM) to satisfy the growing needs of clinicians. PCM was evaluated in vitro and in vivo to demonstrate its capabilities as a barrier membrane for GBR applications. Materials: Peritoneum tissue was cleaned in Triton X-100, rinsed in water, and extracted in acid, base, salt solutions, and alcohols to remove the soluble non-collagenous moieties. The tissue was then treated with purified porcine tendon collagen to convert the fibrous side of the peritoneum to a smooth surface. The treated membrane was crosslinked, sized, packaged, and sterilized. Methods: In Vitro Characterization: SDS-PAGE: SDS-PAGE was performed for collagen typing according to the method of Ramshaw et.al. [1] Hydroxyproline, Elastin, and Desmosine Analyzes: Hydroxyproline and elastin contents in purified peritoneum tissue were determined by the method of Bergman and Loxely [2] and Mecham [3], respectively. Desmosine content in elastin was determined from amino acid analysis. Total collagen content was then calculated based on the data summarized in Table 1. Suture Pull Out Strength: Suture pull-out strength was conducted using a Chatillon mechanical tester at a pulling speed of 2.5cm/min. Conformability: Conformability testing was conducted using standards from the textile industry [4]. Hydrothermal Shrinkage Temperature (Ts): Samples were analyzed using Mettler Toledo DSC. Ts was defined as the onset temperature of the structure change of collagen from triple helix to random coil. In Vivo Intra-Oral Implantation Study: A total of 18 New Zealand White rabbits were used in the study. Two pocket sites at the gum tissue over the maxilla per animal were created and implanted with PCM or a marketed RCM (BioGide, Geistlich) per site. At 4, 8 and 12 weeks, animals were euthanized and explants were collected for histological processing and analysis. Parameters evaluated included implant resorption, new collagen deposition, and host tissue response. Results and Discussion: SDS-PAGE analysis showed that PCM is primarily composed of type I collagen with a minor amount of type III collagen (Fig. 1). From Table 1, the lower hydroxyproline content is consistent with high elastin content present in PCM. High suture pull out strength along with complete conformability allow the membrane to be secured to minimize cell infiltration. The Ts corresponds to the minimal crosslinking of PCM for in vivo stability. The results from the animal study showed that both PCM and BioGide were biocompatible. Both membranes resorbed over time with corresponding new collagen deposition (Fig.2). The estimated complete resorption time for PCM is approximately 12 weeks, about four weeks longer than BioGide (Ts=46oC), consistent with the higher Ts of PCM. Conclusion Results of both the in vitro and in vivo studies provide support that PCM meets the requirements for use as a cell barrier membrane in GBR procedures.