(LR-016) Evaluation of Two Purion Processed Amniotic Tissue Allografts: Bioactivity with Targeted Structural Distinctions

Lisa Godwin, .; Shauna Campbell, BS; Michelle Massee, MS; Thomas Koob, PhD; John Harper, PhD

Introduction: Amniotic membrane allografts have become well established therapeutic approaches for advanced treatment modalities across a broad spectrum of clinical applications. Designing to each of these applications is possible through the development of novel processing techniques and tissue configurations. Depending on the methods used in producing amniotic membrane allografts, differences in composition, protein retention and activity, and physical/handling properties are feasible and attainable.  This study evaluated the membrane properties of two PURION processed amniotic membrane products, a lyophilized human amnion, intermediate layer and chorion membrane (LHACM*) and a dehydrated human amnion, chorion membrane (DHACM**).

Methods:

LHACM and DHACM were prepared using the PURION process, consisting of gentle cleansing, followed by lyophilization (LHACM) or dehydration (DHACM) and terminal sterilization. Thickness was measured using calipers and barrier properties were evaluated using a dialysis chamber. Tissue composition and structural characterization was evaluated using histological analysis. The structure was visualized with hematoxylin and eosin (H&E) staining. Immunofluorescence analysis identified matrix components. Effects on cellular proliferation, migration, and metabolism were assessed using human dermal fibroblasts (HDFs). The host response to the allografts was assessed by subcutaneous implantation in athymic nude mice followed by histopathology of resected grafts and host tissue. 

Results:

Allograft tissue structure was confirmed in both LHACM and DHACM samples. Image analysis identified the presence of collagen type 1 and collagen 4 and an additional, distinct intermediate layer, in LHACM. Soluble factors released from the allografts supported increased cellular proliferation, migration and metabolism.  LHACM is six times thicker than DHACM, however, both allografts were capable of serving as a barrier to prevent the diffusion of high molecular weight proteins. Following subcutaneous implantation, evidence of early infiltration of host cells within the implants and matrix remodeling was associated with the presence of endothelial cells, migrating fibroblasts and new collagen deposition.

Discussion:

The physical and biological properties of an amniotic membrane allograft are determined by the preservation processes employed during manufacture and the inclusion or not of the constituent anatomical layers. PURION processed LHACM and DHACM differ in thickness and handling properties but possess similar in vitro and in vivo activities highlighting the versatility of this processing method. LHACM offers an allograft with the biological properties synonymous with the PURION process, but with alternative structural and handling properties relative to DHACM.

Trademarked Items: *AMNIOEFFECT, MIMEDX Group Inc., Marietta, GA
**EPIFIX, MIMEDX Group Inc. Marietta, GA

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