Characterization of a full-thickness decellularized and lyophilized human placental membrane for clinical applications.

Allografts derived from live-birth tissue obtained with donor consent have emerged as an important treatment option for wound and soft tissue repairs. Placental membrane derived from the amniotic sac consists of the amnion and chorion, the latter of which contains the trophoblast layer. For ease of cleaning and processing, these layers are often separated with or without re-lamination and the trophoblast layer is typically discarded, both of which can negatively affect the abundance of native biological factors and make the grafts difficult to handle. Thus, a full-thickness placental membrane that includes a fully-intact decellularized trophoblast layer was developed for homologous clinical use as a protective barrier and scaffold in soft tissue repairs. Here, we demonstrate that this full-thickness placental membrane is effectively decellularized while retaining native extracellular matrix (ECM) scaffold and biological factors, including the full trophoblast layer. Following processing, it is porous, biocompatible, supports cell proliferation in vitro, and retains its biomechanical strength and the ability to pass through a cannula without visible evidence of movement or damage. Finally, it was accepted as a natural scaffold in vivo with evidence of host-cell infiltration, angiogenesis, tissue remodelling, and structural layer retention for up to 10 weeks in a murine subcutaneous implant model.

Histologic case series of human acellular dermal matrix in superior capsule reconstruction.

BACKGROUND: Acellular dermal matrix (ADM) allografts are commonly used in the surgical treatment of complex and irreparable rotator cuff tears. Multiple studies report that superior capsule reconstruction (SCR) using ADM has resulted in short-term clinical success as assessed via radiographic and patient-reported outcomes. However, limited information is available regarding the biologic fate of these grafts in human subjects. This case series describes histologic results from 8 patients who had reoperations, during which the previously implanted ADMs were removed. These explanted ADMs were subjected to histologic analysis with the hypothesis that they would have evidence of recellularization, revascularization, and active remodeling. METHODS: Eight patients, 38-82 years old, underwent reoperation 6-38 months after undergoing SCR. ADM explants were voluntarily shipped to the manufacturer for histologic analysis. Each graft's structure and composition were qualitatively evaluated by 1 or more of the following histologic stains: hematoxylin and eosin, safranin O, and Russell-Movat pentachrome. Pan-muscle actin staining also assessed the level of neovascularization, potential myoblast or myocyte infiltration, and muscle tissue development in the graft, and was analyzed to determine the proportion of graft that had been recellularized in situ. RESULTS: Grafts showed varying levels of gross and microscopic incorporation with the host. An uneven, but high, overall degree of recellularization, revascularization, and active remodeling was observed. The degree of remodeling correlated with implant duration. These results are consistent with successful biologic reconstruction of the superior shoulder capsule. CONCLUSIONS: The present histologic analysis suggests that ADMs used in SCR undergo active recellularization, revascularization, and remodeling as early as 6 months after implantation, and that graft recellularization positively correlates with duration of implantation. These results represent a significant advancement in our knowledge regarding biologic incorporation of ADMs used in SCR.

The Histology of a Healed Superior Capsular Reconstruction Dermal Allograft: A Case Report.

Acellular human dermal allograft commonly is used in the surgical treatment of complex rotator cuff tears, but little information is known about the biological fate of these grafts in human subjects. In this case report, the authors describe a patient who presented with a radiographically healed acellular human dermal allograft superior capsular reconstruction but had humeral head avascular necrosis. The healed superior capsular reconstruction, including graft-bone interfaces, was explanted after 7 months and sent for histologic analysis. A successful biological reconstruction of the superior capsule was found. The graft demonstrated gross and microscopic incorporation with the host, including a tendon-like structure, aligned collagen fibers, fibroblast-like cells, and no clear graft-host distinction. Cellular infiltration ranged from 5% to 14% (central graft) to 65% to 92% (sutured attachment points). Neovascularization and active graft remodeling were confirmed histologically. LEVEL OF EVIDENCE: V, case report.

Clinical outcome and explant histology after using a cellular bone allograft in two-stage total hip arthroplasty.

BACKGROUND: Although use of cellular bone allografts (CBA) in orthopedic surgery has become increasingly common, little information is available regarding their short-term clinical performance. In these two case reports of two-stage hip arthroplasties, ViviGen Formable CBA (V-CBA) was used in stage one to fill voids left by previous metal implants. METHODS: The two patients had distinctly different health profiles, but each of them had previous metal implants due to a hip fracture. In the otherwise healthy 49-year-old male patient, the total hip arthroplasty (THA) was performed 7 weeks after nail removal and V-CBA backfill. In the 64-year-old female patient with Type 1 diabetes and severe osteoporosis, stage 2 was performed after 12 weeks. At the time of THA for each patient, bone containing some V-CBA was removed to accommodate the hip implant. The explants were histologically analyzed for bone matrix, mineralization, and neovascularization. RESULTS: Histological staining showed substantial new bone formation and neovascularization in both explants albeit at different levels of maturity. CONCLUSIONS: Although limited, these results suggest that V-CBA may facilitate new bone formation in healthy as well as in metabolically challenged patients. LEVEL OF EVIDENCE: V, case report.

Preservation of allograft bone using a glycerol solution: a compilation of original preclinical research.

BACKGROUND: Bone allografts are used in many orthopedic procedures to provide structural stability as well as an osteoconductive matrix for bone ingrowth and fusion. Traditionally, bone allografts have been preserved by either freezing or freeze-drying. Each of these preservation methods has some disadvantages: Frozen grafts require special shipping and storage conditions, and freeze-drying requires special lyophilization equipment and procedures that may impact biomechanical integrity. This report describes an alternate type of preservation using glycerol, which allows storage of fully-hydrated tissues at ambient temperature avoiding the potential complications from freeze-drying. METHODS: In the in vitro three-point bend test, cortical bone was processed and frozen, freeze-dried, or treated with glycerol-based preservation (GBP). Load was applied to each graft at a rate of 2.71 mm/min. The flexural strain, flexural strength, and flexural modulus were then calculated. In the in vitro axial compression test, iliac crest wedges, fibular segments, and Cloward dowels were processed and either freeze-dried or GBP treated. The compressive strength of the grafts were tested at time zero and after real time aging of 1, 4, and 5 years. In the in vivo rat calvarial defect assessment, freeze-dried, frozen, and GBP bone implants were compared after being implanted into a critical sized defect. Samples underwent histological and biomechanical evaluation. RESULTS: Bone grafts subjected to GBP were found to be at least biomechanically equivalent to frozen bone while also being significantly less brittle than freeze-dried bone. GBP-preserved bone demonstrated significantly greater compressive strength than freeze-dried at multiple time points. Preclinical research performed in calvaric defect models found that GBP-preserved bone had similar osteoconductivity and biocompatibility to frozen and freeze-dried samples. CONCLUSION: Preclinical research demonstrated that glycerol-preservation of bone yields a material that maintains biomechanical strength while eliminating the need for extensive rehydration or thaw periods if used clinically. Additionally, in vivo evidence suggests no negative impact of glycerol-preservation on the ability of bone grafts to successfully participate in new bone formation and fusion.