Understanding the Impact of Preservation Methods on the Integrity and Functionality of Placental Allografts

Exploring the Efficacy of Selected Allografts in Chronic Wound Healing: Evidence from Murine Models and Clinical Data for a Proposed Treatment Algorithm

Significance: Chronic wounds can lead to poor outcomes for patients, with risks, including amputation and death. In the United States, chronic wounds affect 2.5% of the population and cost up to $28 billion per year in primary health care costs. Recent Advances: Allograft tissues (dermal, amnion, and amnion/chorion) have shown efficacy in improving healing of chronic, recalcitrant wounds in human patients, as evidenced by multiple clinical trials. Their mechanisms of actions have been relatively understudied, until recently. Research in murine models has shown that dermal allografts promote reepithelialization, amnion allografts promote granulation tissue formation and angiogenesis, and amnion/chorion allografts support all stages of wound healing. These findings confirm their effectiveness and illuminate their therapeutic mechanisms. Critical Issues: Despite the promise of allografts in chronic wound care, a gap exists in understanding which allografts are most effective during each wound healing stage. The variable efficacy among each type of allograft suggests a mechanistic approach toward a proposed clinical treatment algorithm, based on wound characteristics and patient's needs, may be beneficial. Future Directions: Recent advances in allografts provide a framework for further investigations into patient-specific allograft selection. This requires additional research to identify which allografts support the best outcomes during each stage of wound healing and in which wound types. Longitudinal human studies investigating the long-term impacts of allografts, particularly in the remodeling phase, are also essential to developing a deeper understanding of their role in sustained wound repair and recovery.

Biological study of skin wound treated with Alginate/Carboxymethyl cellulose/chorion membrane, diopside nanoparticles, and Botox A

A hydrogel-based wound dressing with desirable properties is necessary for achieving functional skin integrity post-injury. This study focuses on preparing a hydrogel using Alginate/Carboxymethyl cellulose (Alg/CMC) as a base material. To evaluate its regenerative effects on full-thickness wounds, diopside nanoparticles and Botulinum toxin A (BTX-A) were incorporated into the hydrogel along with chorion membrane. The diopside nanoparticles (DNPs) act as a proangiogenic factor, promoting proliferation and regulating inflammation, while the chorion membrane facilitates these processes. Additionally, BTX-A prevents scar formation and aids in wound closure. The nanoparticles and hydrogel were characterized using various techniques, and their cytocompatibility was assessed. In vivo studies and quantitative polymerase chain reaction analysis showed that wound area reduction was significant after two weeks of treatment with the Alg/CMC/ChNPs/DNPs/BTX-A hydrogel. Overall, this scaffold demonstrated potential for promoting tissue regeneration and new epithelization formation, making it a promising candidate for enhancing skin restoration in wound treatments.

Retention of Key Characteristics of Unprocessed Chorion Tissue Resulting in a Robust Scaffold to Support Wound Healing

Placental membranes have been widely studied and used clinically for wound care applications, but there is limited published information on the benefits of using the chorion membrane. The chorion membrane represents a promising source of placental-derived tissue to support wound healing, with its native composition of extracellular matrix (ECM) proteins and key regulatory proteins. This study examined the impact of hypothermic storage on the structure of chorion membrane, ECM content, and response to degradation in vitro. Hypothermically stored chorion membrane (HSCM) was further characterized for its proteomic content, and for its functionality as a scaffold for cell attachment and proliferation in vitro. HSCM retained the native ECM structure, composition, and integrity of native unprocessed chorion membrane and showed no differences in response to degradation in an in vitro wound model. HSCM retained key regulatory proteins previously shown to be present in placental membranes and promoted the attachment and proliferation of fibroblasts in vitro. These data support the fact that hypothermic storage does not significantly impact the structure and characteristics of the chorion membrane compared to unprocessed tissue or its functionality as a scaffold to support tissue growth.

Quantification of Analgesic and Anti-Inflammatory Lipid Mediators in Long-Term Cryopreserved and Freeze-Dried Preserved Human Amniotic Membrane

The aim of this study was to compare concentrations of endogenous N-acylethanolamine (NAE) lipid mediators-palmitoylethanolamide (PEA), oleoylethanolamide (OEA), and anandamide (AEA)-in fresh, decontaminated, cryopreserved, and freeze-dried amniotic membrane (AM) allografts, thereby determining whether AM's analgesic and anti-inflammatory efficiency related to NAEs persists during storage. The concentrations of NAEs were measured using ultra-high-performance liquid chromatography-tandem mass spectrometry. Indirect fluorescent immunohistochemistry was used to detect the PEA PPAR-α receptor. The concentrations of PEA, OEA, and AEA were significantly higher after decontamination. A significant decrease was found in cryopreserved AM compared to decontaminated tissue for PEA but not for OEA and AEA. However, significantly higher values for all NAEs were detected in cryopreserved samples compared to fresh tissue before decontamination. The freeze-dried AM had similar values to decontaminated AM with no statistically significant difference. The nuclear staining of the PPAR-α receptor was clearly visible in all specimens. The stability of NAEs in AM after cryopreservation was demonstrated under tissue bank storage conditions. However, a significant decrease, but still higher concentration of PEA compared to fresh not decontaminated tissue, was found in cryopreserved, but not freeze-dried, AM. Results indicate that NAEs persist during storage in levels sufficient for the analgesic and anti-inflammatory effects. This means that cryopreserved AM allografts released for transplant purposes before the expected expiration (usually 3-5 years) will still show a strong analgesic effect. The same situation was confirmed for AM lyophilized after one year of storage. This work thus contributed to the clarification of the analgesic effect of NAEs in AM allografts.

Amnion membranes support wound granulation in a delayed murine excisional wound model

Chronic or delayed healing wounds constitute an ever-increasing burden on healthcare providers and patients alike. Thus, therapeutic modalities that are tailored to particular deficiencies in the delayed wound healing response are of critical importance to improve clinical outcomes. Human amnion-derived viable and devitalized allografts have demonstrated clinical efficacy in promoting the closure of delayed healing wounds, but the mechanisms responsible for this efficacy and the specific wound healing processes modulated by these tissues are not fully understood. Here, we utilized a diabetic murine excisional wound model in which healing is driven by granulation and re-epithelialization, and we applied viable (vHAMA) or devitalized (dHAMA) amnion-derived allografts to the wound bed in order to determine their effects on wound healing processes. Compared to control wounds that were allowed to heal in the absence of treatment, wounds to which vHAMA or dHAMA were applied demonstrated enhanced deposition of granulation tissue accompanied by increased cellular proliferation and increased de novo angiogenesis, while vHAMA-treated wounds also demonstrated accelerated re-epithelialization. Taken together, these data suggest that both vHAMA and dHAMA facilitate wound healing through promoting processes critical to granulation tissue formation. Further understanding of the cellular and tissue mechanisms underlying the effects of tissue-derived matrices on wound healing will enable tailored prescription of their use in order to maximize clinical benefit.

The Use of Quercetin to Improve the Antioxidant and Regenerative Properties of Frozen or Cryopreserved Human Amniotic Membrane

The biological properties of the human amniotic membrane (HAM) and its characteristic ability to be a reservoir of growth factors promoting wound healing make it an ideal biological dressing for the treatment of different clinical conditions, such as burns and non-healing wounds. However, the application of a preservation method on the HAM is required during banking to maintain biological tissue properties and to ensure the release overtime of protein content for its final clinical effectiveness after application on the wound bed. Although cryopreservation and freezing are methods widely used to maintain tissue properties, reactive oxygen species (ROS) are produced within tissue cellular components during their switching from frozen to thawed state. Consequently, these methods can lead to oxidative stress-induced cell injury, affecting tissue regenerative properties and its final clinical effectiveness. Taking advantage of the antioxidant activity of the natural compound quercetin, we used it to improve the antioxidant and regenerative properties of frozen or cryopreserved HAM tissues. In particular, we evaluated the oxidative damage (lipid peroxidation, malondialdehyde) as well as the regenerative/biological properties (bFGF growth factor release, wound healing closure, structure, and viability) of HAM tissue after its application. We identified the effectiveness of quercetin on both preservation methods to reduce oxidative damage, as well as its ability to enhance regenerative properties, while maintaining the unaltered structure and viability of HAM tissue. The use of quercetin described in this study appears able to counteract the side effects of cryopreservation and freezing methods related to oxidative stress, enhancing the regenerative properties of HAM. However, further investigations will need to be performed, starting from these promising results, to identify its beneficial effect when applied on burns or non-healing wounds.

Healing of a chronic ulcer of the lower limb of venous origin with fresh human amniochorionic membrane allograft

In its fresh state, the amniochorionic membrane contains various multipotential cells, growth factors, and extracellular matrix proteins that contribute to the healing of chronic vascular ulcers. To demonstrate its effectiveness, a fresh human placental membrane allograft was applied to a chronic venous ulcer in the lower limb of an 89-year-old female patient with a 12 x 10 cm ulcerated lesion of 40 years of evolution in the malleolar area of her left lower limb. Sixty days after the graft, the ulcer was healed in 100% of its surface and a light pink scar on the edges indicated possible pigmentation. Fresh human amniochorionic membrane allograft is a therapeutic alternative for the healing of refractory chronic vascular ulcers of the lower extremities.

Placental Tissues as Biomaterials in Regenerative Medicine

Placental tissues encompass all the tissues which support fetal development, including the placenta, placental membrane, umbilical cord, and amniotic fluid. Since the 1990s there has been renewed interest in the use of these tissues as a raw material for regenerative medicine applications. Placental tissues have been extensively studied for their potential contribution to tissue repair applications. Studies have attributed their efficacy in augmenting the healing process to the extracellular matrix scaffolds rich in collagens, glycosaminoglycans, and proteoglycans, as well as the presence of cytokines within the tissues that have been shown to stimulate re-epithelialization, promote angiogenesis, and aid in the reduction of inflammation and scarring. The compositions and properties of all birth tissues give them the potential to be valuable biomaterials for the development of new regenerative therapies. Herein, the development and compositions of each of these tissues are reviewed, with focus on the structural and signaling components that are relevant to medical applications. This review also explores current configurations and recent innovations in the use of placental tissues as biomaterials in regenerative medicine.

Biophysical Characterization of a Novel Tri-Layer Placental Allograft Membrane

Objective: Placental tissues, including membranes composed of amnion and chorion, are promising options for the treatment of chronic wounds. Amnion and chorion contain multiple extracellular matrix (ECM) proteins and a multitude of growth factors and cytokines that, when used clinically, assist in the progression of difficult to heal wounds through restoration of a normal healing process. The objective of this study was to characterize the in vitro physical and biological properties of a dehydrated tri-layer placental allograft membrane (TPAM) consisting of a chorion layer sandwiched between two layers of amnion. Approach: Mechanical properties were evaluated by mechanical strength and enzyme degradation assays. The ECM composition of TPAM membranes was evaluated by histological staining while growth factors and cytokine presence was evaluated by a multiplex enzyme-linked immunosorbent assay. Proliferation, migration, and ECM secretion assays were performed with fibroblasts. Immunomodulatory properties were assessed by a pro-inflammatory cytokine reduction assay while the macrophage phenotype was determined by quantifying the ratio of M1 versus M2 secreted factors. Results: The unique three-layer construction improves mechanical handling properties over single- and bi-layer membranes. Results demonstrate that TPAM is rich in ECM proteins, growth factors, cytokines, and tissue inhibitors of metalloproteinases, and favorably influences fibroblast migration, proliferation, and ECM secretion when compared to negative controls. Furthermore, after processing and preservation, these membranes maintain their intrinsic immunomodulatory properties with the ability to suppress pro-inflammatory processes and modulate the M1 and M2 macrophage phenotype toward a pro-regenerative profile when compared to a negative control. Innovation: This is the first study to characterize both the biophysical and biological properties of a tri-layer placental membrane. Conclusion: This work demonstrates that TPAM has improved handling characteristics over single- and bi-layer membranes, stimulates pro-healing cellular responses, and advantageously modulates inflammatory responses, altogether making this scaffold a promising option for treating wounds, especially those that are complex or difficult to heal.

The healing dynamics of non-healing wounds using cryo-preserved amniotic membrane

We evaluated the effect of the application of cryo‐preserved amniotic membrane on the healing of 26 non‐healing wounds (18 patients) with varying aetiologies and baseline sizes (average of 15.4 cm²), which had resisted the standard of care treatment for 6 to 456 weeks (average 88.8 weeks). Based on their average general responses to the application of cryo‐preserved AM, we could differentiate three wound groups. The first healed group was characterised by complete healing (100% wound closure, maximum treatment period 38 weeks) and represented 62% of treated wounds. The wound area reduction of at least 50% was reached for all wounds in this group within the first 10 weeks of treatment. Exactly 19% of the studied wounds responded partially to the treatment (partially healed group), reaching less than 25% of closure in the first 10 weeks and 90% at maximum for extended treatment period (up to 78 weeks). The remaining 19% of treated wounds did not show any reaction to the AM application (unhealed defects). The three groups have different profiles of wound area reduction, which can be used as a guideline in predicting the healing prognosis of non‐healing wounds treated with a cryo‐preserved amniotic membrane.

Effects of Preservation Methods in the Composition of the Placental and Reflected Regions of the Human Amniotic Membrane

The human amniotic membrane (AM) is emerging as an interesting biomaterial for regenerative medicine due to its biological and mechanical proprieties. The beneficial effects of the AM are probably related to its bioactive factors produced by local cells and stored in the stromal matrix. However, the search for a preservation method capable of preserving AM properties remains a challenge. The aim of this study was to evaluate important features of 2 anatomical regions of the human AM (reflected and placental amnion) after different preservation methods. For this purpose, human placentas were harvested and processed for AM isolation and storage at 2 different conditions: room temperature for 18 h in DMEM (fresh AM) and -80°C in DMEM/glycerol solution for 30 days (cryopreserved AM). After the storage period, the structural integrity of the membrane was assessed by histological and Picrosirius polarization analysis, cellular viability analysis was performed using the MTT assay, and the soluble proteins were quantified with the Qubit Protein Assay Kit. Both preservation protocols reduced the cell viability, mainly in the placental amnion region of the AM, but preserved the morphology of epithelial and stromal layers, as well as the organization and distribution of collagen fibers. There was a reduction in soluble proteins only in fresh AM. Importantly, the cryopreserved AM group presented the same concentration as the control group. In conclusion, the cryopreservation using DMEM/glycerol was ideal for preserving the structural integrity and soluble protein content, indicating the feasibility of this method in preserving AM for its use in regenerative medicine.

Comprehensive Comparison of Amnion Stromal Cells and Chorion Stromal Cells by RNA-Seq

Mesenchymal stromal cells derived from the fetal placenta, composed of an amnion membrane, chorion membrane, and umbilical cord, have emerged as promising sources for regenerative medicine. Here, we used next-generation sequencing technology to comprehensively compare amniotic stromal cells (ASCs) with chorionic stromal cells (CSCs) at the molecular and signaling levels. Principal component analysis showed a clear dichotomy of gene expression profiles between ASCs and CSCs. Unsupervised hierarchical clustering confirmed that the biological repeats of ASCs and CSCs were able to respectively group together. Supervised analysis identified differentially expressed genes, such as LMO3, HOXA11, and HOXA13, and differentially expressed isoforms, such as CXCL6 and HGF. Gene Ontology (GO) analysis showed that the GO terms of the extracellular matrix, angiogenesis, and cell adhesion were significantly enriched in CSCs. We further explored the factors associated with inflammation and angiogenesis using a multiplex assay. In comparison with ASCs, CSCs secreted higher levels of angiogenic factors, including angiogenin, VEGFA, HGF, and bFGF. The results of a tube formation assay proved that CSCs exhibited a strong angiogenic function. However, ASCs secreted two-fold more of an anti-inflammatory factor, TSG-6, than CSCs. In conclusion, our study demonstrated the differential gene expression patterns between ASCs and CSCs. CSCs have superior angiogenic potential, whereas ASCs exhibit increased anti-inflammatory properties.

The Role of Collagen-Based Biomaterials in Chronic Wound Healing and Sports Medicine Applications

Advancements in tissue engineering have taken aim at treating tissue types that have difficulty healing naturally. In order to achieve improved healing conditions, the balance of exogenous matrix, cells, and different factors must be carefully controlled. This review seeks to explore the aspects of tissue engineering in specific tissue types treated in sports medicine and advanced wound management from the perspective of the matrix component. While the predominant material to be discussed is collagen I, it would be remiss not to mention its relation to the other contributing factors to tissue engineered healing. The main categories of materials summarized here are (1) reconstituted collagen scaffolds, (2) decellularized matrix tissue, and (3) non-decellularized tissue. These three groups are ordered by their increase in additional components beyond simply collagen.

Long-term preservation effects on biological properties of acellular placental sponge patches

Decellularization, preservation protocol and storage time influence the biomechanical and biological properties of allografts and xenografts. Here, we examined the consequences of storage time on the antibacterial, angiogenic and biocompatibility properties of the decellularized placental sponge (DPS) in vitro and in vivo. The DPS samples were preserved for one, three and six months at -20 °C. The decellularized scaffolds showed uniform morphology with interconnected pores compared with not decellularized sponges. Storage time did not interfere with collagen and vascular endothelial growth factor contents, and cytobiocompatibility for Hu02 fibroblast cells. Chorioallantoic membrane assay and subcutaneous implantation indicated a decreased new vessel formation and neovascularization in six months DPS sample compared with other experimental groups. The number of CD4⁺ and CD68⁺ cells infiltrated into the six months DPS on the implanted site showed a significant increase compared with one and three months sponges. The antibacterial activities and angiogenic properties of the DPS decreased over storage time. Three months preservation at -20 °C is suggested as the optimal storage period to retain its antibacterial activity and high stimulation of new vessel formation. This storage protocol could be considered for preservation of similar decellularized placenta-derived products with the aim of retaining their biological properties.

Human Amniotic Membrane: A review on tissue engineering, application, and storage

Human amniotic membrane (hAM) has been employed as scaffolding material in a wide range of tissue engineering applications, especially as a skin dressing and as a graft for corneal treatment, due to the structure of the extracellular matrix and excellent biological properties that enhance both wound healing and tissue regeneration. This review highlights recent work and current knowledge on the application of native hAM, and/or production of hAM-based tissue-engineered products to create scaffolds mimicking the structure of the native membrane to enhance the hAM performance. Moreover, an overview is presented on the available (cryo) preservation techniques for storage of native hAM and tissue-engineered products that are necessary to maintain biological functions such as angiogenesis, anti-inflammation, antifibrotic and antibacterial activity.

Structural and Functional Equivalency Between Lyopreserved and Cryopreserved Chorions with Viable Cells

Objective: Clinical studies have demonstrated that the use of cryopreserved amnion or trophoblast (TR)-free chorion, containing viable cells, in the treatment of chronic wounds results in high rate of wound closure. Recently, a new lyopreservation method has been developed for preservation of amnion that also retains the endogenous viable cells. The objective of this study was to use this method for lyopreservation of TR-free chorionic membrane (viable lyopreserved chorionic membrane [VLCM]) and compare it with the viable cryopreserved chorionic membrane (VCCM). A second objective was to investigate the immunogenicity of chorion, an important question that has not been fully addressed.

Approach: Chorion immunogenicity was tested in vitro in a mixed lymphocyte reaction and lipopolysaccharide (LPS) challenge assay, and in vivo in a mouse subcutaneous pocket implantation model. VLCM tissue structure was assessed histologically, growth factor content by multiplex assay, and cell viability by LIVE/DEAD cell fluorescent staining. Inhibition of tumor necrosis factor α secretion by LPS-activated THP-1 cells and endothelial cell tubule formation assays were performed to evaluate the anti-inflammatory and proangiogenic properties, respectively. An in vivo rabbit abdominal adhesion model was used to evaluate the antifibrotic properties.

Results: Chorionic membrane without trophoblast (CM) was shown to be nonimmunogenic. Tissue architecture, growth factors, and cell viability of fresh CM were maintained in VLCM and VCCM. In vitro studies showed that anti-inflammatory and angiogenic properties were retained in VLCM. Furthermore, VLCM prevents formation of postsurgical adhesions in a rabbit abdominal surgical adhesion model.

Innovation: Characterization of structural and functional properties of VLCM is reported for the first time.

Conclusion: Similar to VCCM, VLCM retains native components of fresh CM, including collagen-rich extracellular matrix, growth factors, and viable cells. In vitro and in vivo models demonstrate that VLCM is anti-inflammatory, proangiogenic and antifibrotic. Results of this study support the structural and functional equivalency between VLCM and VCCM.

Lyopreserved amniotic membrane is cellularly and clinically similar to cryopreserved construct for treating foot ulcers

We compared cellular viability between cryopreserved and lyopreserved amniotic membranes and clinical outcomes of the lyopreserved construct in a prospective cohort study of 40 patients with neuropathic foot ulcers. Patients received weekly application of lyopreserved membrane for 12 weeks with standard weekly debridement and offloading. We evaluated the proportion of foot ulcers that closed, time to closure, closure trajectories, and infection during therapy. We used chi-square tests for dichotomous variables and independent t-tests for continuous variables with an alpha of α = .10. Cellular viability was equivalent between cryo- and lyopreserved amniotic tissues. Clinically, 48% of subjects' wounds closed in an average of 40.0 days. Those that did not close were older (63 vs 59 years, P = .011) and larger ulcers at baseline (7.8 vs 1.6 cm² , P = .012). Significantly more patients who achieved closure reached a 50% wound area reduction in 4 weeks compared with non-closed wounds (73.7% vs 47.6%, P = .093). There was no difference in the slope of the wound closure trajectories between closed and non-closed wounds (0.124 and 0.159, P = .85), indicating the rate of closure was similar. The rate of closure was 0.60 mm/day (SD = 0.47) for wounds that closed and 0.50 mm/day (SD = 0.58) for wounds that did not close (P = .89).

Intermediate layer contribution in placental membrane allografts

Placental membrane (PM) allografts are commonly used to treat chronic wounds. Native PM is composed of an amnion, chorion, and intermediate layer (IL) that contain matrix structures and regulatory components beneficial in wound healing. Historically, commercially available allografts were composed of only one or two layers of the PM. To maximize the conserved material in PM allografts, a dehydrated complete human placental membrane (dCHPM) allograft processed using the Clearify™ process was developed. Histological and proteomic characterization comparing dCHPM allografts with native PM demonstrated that the majority of matrix structures and regulatory proteins are retained in dCHPM allografts through processing. To evaluate the importance of maintaining the entire intact PM and the contribution of the IL, the structural and proteomic makeup of the IL was compared with that of dCHPM allografts. This is the first known characterization of regulatory proteins in the IL. Results demonstrate that the IL contains over 900 regulatory and signaling components, including chemokines, growth factors, interleukins, and protease inhibitors. These components are key regulators of angiogenesis, neurogenesis, osteogenesis, inflammation, tissue remodeling, and host defense. The results show that the proteomic composition of the IL is consistent with that of the entire dCHPM allograft. Although further investigation is required to fully understand the contribution of the IL in PM allografts, these results demonstrate that the IL contains structural and regulatory proteins that can enhance the barrier and wound healing properties of PM allografts.

A Flowable Placental Formulation Prevents Bleomycin-Induced Dermal Fibrosis in Aged Mice

Fibrosis, the thickening and scarring of injured connective tissue, leads to a loss of organ function. Multiple cell types, including T-cells, macrophages, fibrocytes, and fibroblasts/myofibroblasts contribute to scar formation via secretion of inflammatory factors. This event results in an increase in oxidative stress and deposition of excessive extracellular matrix (ECM), characteristic of fibrosis. Further, aging is known to predispose connective tissue to fibrosis due to reduced tissue regeneration. In this study, we investigated the anti-fibrotic activity of a flowable placental formulation (FPF) using a bleomycin-induced dermal fibrosis model in aged mice. FPF consisted of placental amnion/chorion- and umbilical tissue-derived ECM and cells. The mice were injected with either FPF or PBS, followed by multiple doses of bleomycin. Histological assessment of FPF-treated skin samples revealed reduced dermal fibrosis, inflammation, and TGF-β signaling compared to the control group. Quantitative RT-PCR and Next Generation Sequencing analysis of miRNAs further confirmed anti-fibrotic changes in the FPF-treated group at both the gene and transcriptional levels. The observed modulation in miRNAs was associated with inflammation, TGF-β signaling, fibroblast proliferation, epithelial-mesenchymal transition and ECM deposition. These results demonstrate the potential of FPF in preventing fibrosis and may be of therapeutic benefit for those at higher risk of fibrosis due to wounds, aging, exposure to radiation and genetic predisposition.

Endogenous viable cells in lyopreserved amnion retain differentiation potential and anti-fibrotic activity in vitro

Human amniotic membrane (AM) has intrinsic anti-inflammatory, anti-fibrotic and antimicrobial properties. Tissue preservation methods have helped to overcome the short shelf life of fresh AM allowing "on demand" use of AM grafts. Cryopreserved AM that retains all native tissue components, including viable cells, has clinical benefits in treating chronic wounds. However, cryopreservation requires ultra-low temperature storage, limiting the use of cryopreserved products. To overcome this limitation, a new lyopreservation method has been developed for ambient storage of living tissues. The goal of this study was to investigate the viability and functionality of AM cells following lyopreservation. Fresh AM and devitalized lyopreserved AM (DLAM) served as positive and negative controls, respectively. Using live/dead staining, we confirmed the presence of living cells in viable lyopreserved AM (VLAM) and showed that these cells persisted up to 21 days in culture medium. The functionality of cells in VLAM was assessed by their differentiation potential and anti-fibrotic activity in vitro. With osteogenic induction, cells in VLAM deposited calcium within the membrane, a marker of osteogenic cells, in a time-dependent manner. The migration of human lung fibrotic fibroblasts in a scratch wound assay was reduced significantly in the presence of VLAM-derived conditioned medium. Quantitative PCR analyses indicated that VLAM reduced the expression of pro-fibrotic factors such as type I collagen and increased the expression of anti-fibrotic factors such as hepatocyte growth factor and anti-fibrotic microRNA in fibrotic fibroblasts. Taken together, these results demonstrate that endogenous cells in VLAM remain viable and functional post-lyophilization. STATEMENT OF SIGNIFICANCE: This study, for the first time, provides direct evidence showing that tissue viability and functional cells can be preserved by lyophilization. Similar to fresh amniotic membrane (AM), viable lyopreserved AM (VLAM) retains viable cells for extended periods of time. More importantly, these cells are functional and maintain their osteogenic differentiation potential and anti-fibrotic activity. Our results confirmed that the novel lyophilization method preserves tissue viability.

Characterisation of dehydrated amnion chorion membranes and evaluation of fibroblast and keratinocyte responses in vitro

The purpose of this study is to characterise the composition of a dehydrated amnion and chorion graft and investigate how factors released from this graft interact with cells important to the wound microenvironment using in vitro models. Characterisation was completed by proteomic analysis of growth factors and cytokines, evaluation of matrix components and protease inhibition, immunohistochemistry, and in vitro release of key growth factors and cytokines. To evaluate the effect of released factors on cells found within the microenvironment, in vitro assays including: cell proliferation, migration, gene expression, protein production, and intracellular pathway activation were used; additionally, responses of fibroblasts in the context of inflammation were measured. We found that released factors from dehydrated amnion/chorion membranes (dACM) stimulated cell proliferation, migration, and altered gene and protein expression profiles of cells important for wound repair in vitro. When cells were cultured in the presence of pro‐inflammatory cytokines, the addition of releasate from dACM resulted in an altered production of cytokines, including a reduction of pro‐inflammatory regulated on activation, normal T cell expressed and secreted (RANTES). In sum, the results presented here characterise the components of dACM, and in vitro studies were used to evaluate interactions of dACM with cell types important in wound healing.

Management of a chronic radiation necrosis wound with lyopreserved placental membrane containing viable cells

This case report describes management of a chronic radiation wound in a patient with multiple comorbidities using a lyopreserved placental membrane containing viable cells (vLPM). Positive outcomes suggest that vLPM provides a good conservative management option for patients with compromised wound healing due to radiation and comorbidities.

A quality improvement pilot assessment of the safety and associated outcomes of a viable cryopreserved umbilical tissue allograft as an adjunct surgical wrap in peroneus brevis tendon repair

Surgical tendon repairs of the lower extremity are frequently associated with post-operative (post-op) risks that result in poor patient outcomes. Initially, increased pain levels may contribute to extended post-op rehabilitation while the development of tissue adhesions and fibrosis limit long-term functionality through reduced range of motion. Several surgical methods describing incorporation of various augmentative graft materials in tendon repair exist. However, reports demonstrating technique and both short- and long-term patient outcomes are lacking. Recently, advances in tissue preservation technology have led to the commercialization of human placental allografts. Of these available allogeneic biomaterials, the components found in human placental membranes may provide anti-inflammatory, antimicrobial, anti-adhesive, and antifibrotic properties to benefit surgical outcomes.Here, the authors introduce and technically describe the use of a viable cryopreserved umbilical tissue (vCUT) (Stravix, Osiris Therapeutics, Inc., Columbia, MD) as a complementary surgical wrap in primary tendon repair, with particular focus on the peroneus brevis. A pilot study was undertaken to assess the safety and potential for secondary rehabilitative outcomes associated with the use of vCUT in 5 tendon repair cases. The use of vCUT as a surgical tendon wrap was evaluated via the following primary endpoints at post-op day 7:Secondary investigative endpoints included clinical and rehabilitative outcome measures for comparative pain reduction and transition times to both controlled ankle movement (CAM) boot and normal shoe ambulation.All patients were followed for an average of 24.15 months (range 16.75-26.5 months) after surgery. For primary safety measures, erythema, tenderness, drainage, heat, and swelling was absent in all 5 surgical sites. None of the patients required post-op use of narcotics past day 7. The potential for long-term rehabilitative improvement with adjunct use of vCUT was also demonstrated through reduced pain and reduced transition times to functional and non-assisted ambulation in normal shoewear as compared to historical controls managed without vCUT.This surgical technique is simple and safe for patients and preliminary findings have demonstrated favorable clinical and rehabilitative outcomes over historically observed controls.

Nonsurgical management of a large necrotic nasal tip wound using a viable cryopreserved placental membrane

A large necrotic nasal wound with interdomal subcutaneous tissue loss and the exposed greater alar cartilage was managed conservatively with a placental allograft. This approach is an alternative to the complex staged surgical reconstructive procedures for poor surgical candidates, patients unwilling to undergo facial surgeries, or autologous nasal graft failures.

Viable cryopreserved umbilical tissue (vCUT) reduces post-operative adhesions in a rabbit abdominal adhesion model

Post-operative adhesions, a common complication of surgery, cause pain, impair organ functionality, and often require additional surgical interventions. Control of inflammation, protection of injured tissue, and rapid tissue repair are critical for adhesion prevention. Adhesion barriers are biomaterials used to prevent adhesions by physical separation of opposing injured tissues. Current adhesion barriers have poor anti-inflammatory and tissue regenerative properties. Umbilical cord tissue (UT), a part of the placenta, is inherently soft, conforming, biocompatible, and biodegradable, with antimicrobial, anti-inflammatory, and antifibrotic properties, making it an attractive alternative to currently available adhesion barriers. While use of fresh tissue is preferable, availability and short storage time limit its clinical use. A viable cryopreserved UT (vCUT) "point of care" allograft has recently become available. vCUT retains the extracellular matrix, growth factors, and native viable cells with the added advantage of a long shelf life at -80 °C. In this study, vCUT's anti-adhesion property was evaluated in a rabbit abdominal adhesion model. The cecum was abraded on two opposing sides, and vCUT was sutured to the abdominal wall on the treatment side; whereas the contralateral side of the abdomen served as an internal untreated control. Gross and histological evaluation was performed at 7, 28, and 67 days post-surgery. No adhesions were detectable on the vCUT treated side at all time points. Histological scores for adhesion, inflammation, and fibrosis were lower on the vCUT treated side as compared to the control side. In conclusion, the data supports the use of vCUT as an adhesion barrier in surgical procedures.

Properties of viable lyopreserved amnion are equivalent to viable cryopreserved amnion with the convenience of ambient storage

Human amniotic membrane (AM) has a long history of clinical use for wound treatment. AM serves as a wound protective barrier maintaining proper moisture. AM is anti-inflammatory, anti-microbial and antifibrotic, and supports angiogenesis, granulation tissue formation and wound re-epithelialization. These properties of AM are attributed to its native extracellular matrix, growth factors, and endogenous cells including mesenchymal stem cells. Advances in tissue preservation have helped to overcome the short shelf life of fresh AM and led to the development of AM products for clinical use. Viable cryopreserved amnion (VCAM), which retains all native components of fresh AM, has shown positive outcomes in clinical trials for wound management. However, cryopreservation requires ultra-low temperature storage and shipment that limits widespread use of VCAM. We have developed a lyopreservation technique to allow for ambient storage of living tissues. Here, we compared the structural, molecular, and functional properties of a viable lyopreserved human amniotic membrane (VLAM) with properties of VCAM using in vitro and in vivo wound models. We found that the structure, growth factors, and cell viability of VLAM is similar to that of VCAM and fresh AM. Both, VCAM and VLAM inhibited TNF-α secretion and upregulated VEGF expression in vitro under conditions designed to mimic inflammation and hypoxia in a wound microenvironment, and resulted in wound closure in a diabetic mouse chronic wound model. Taken together, these data demonstrate that VLAM structural and functional properties are equivalent to VCAM but without the constraints of ultra-low temperature storage.

Effectiveness of viable cryopreserved placental membranes for management of diabetic foot ulcers in a real world setting

In a multicenter randomized controlled trial (RCT), the use of viable cryopreserved placental membrane (vCPM) for chronic diabetic foot ulcers (DFUs) resulted in a higher proportion of wound closure in comparison to good wound care: 62% versus 21% (p < 0.01). However, patients in RCTs are not representative of daily physician practice. Healthcare databases serve as a valuable tool to evaluate therapy effectiveness and to supplement evidence from RCTs. The objective of this study was to evaluate the effectiveness of vCPM for DFU management using Net Health's WoundExpert® electronic health records (EHR). The primary endpoint was the proportion of DFUs that achieved complete closure. Other endpoints included time and number of grafts to closure, probability of wound closure by week 12, and the number of wound-related infections and amputations. De-identified EHR data for 360 patients with 441 wounds treated with vCPM were extracted from the database. Average patient age was 63.7 years with a mean wound size of 5.1 cm² and an average wound duration of 102 days prior to vCPM treatment. For evaluation of clinical outcomes, 350 DFUs larger than 0.25 cm² at baseline were analyzed. Closure at the end of treatment was achieved in 59.4% of wounds with a median treatment duration of 42.0 days and 4 applications of vCPM. The probability of wound closure at week 12 was 71%, and the number of amputations and wound-related infections was 13 (3.0%) and 9 (2.0%), respectively. Data also demonstrated a correlation between wound size and closure rate as well as a correlation between > 50% wound area reduction by week 4 and wound closure by week 12. The results of this study mirror previous RCT efficacy data, supporting the benefits of vCPM for DFU management. These results can also influence policy and treatment decisions regarding advanced vCPM technology.

A case of Dupuytren's disease managed with viable cryopreserved placental membrane adjunct to open palmar fasciectomy

Dupuytren's disease (DD) is a rare connective tissue disorder resulting in progressive fibrosis and thickening of the palmar fascia, and contracture of the fingers due to excessive collagen deposition. Staged surgical interventions are reserved for severe cases, yet worsening of fibrosis and contracture of fingers post-surgery, has been reported to have a recurrence rate as high as 85%. Here, the authors report on use of viable cryopreserved placental membrane (vCPM) allograft as an adjunct to open fasciectomy. In a patient with debilitating bilateral DD contractures of >20 years duration, this novel approach resulted in a 34.8% range of motion (ROM) improvement and ability to fully extend all digits of the right hand. No adverse events were recorded. At 1 year post-surgery, the patient has no decrease in ROM. Results indicate that vCPM incorporation in open fasciectomy may provide benefit in reducing contracture recurrence in DD patients.

Use of Viable Cryopreserved Placental Membrane as an Adjunct to Facial Keloid Resection

Keloids are the physical manifestation of an exaggerated inflammatory response resulting in excess collagen deposition. The resulting fibroproliferative mass can be distressing for patients due to appearance, pruritus, and/or pain. Despite extensive research into the pathophysiology of keloid formation and the development of numerous treatments, keloids remain a challenge to treat. Even when the initial treatment is successful, a risk of recurrence remains. Basic science research into viable cryopreserved placental membranes and viable cryopreserved umbilical tissue has demonstrated their anti-inflammatory and anti-fibrotic effects, which may decrease keloid recurrence after excision. In this article, we present the first-reported case of viable cryopreserved placental membrane, with living mesenchymal stem cells, to treat a painful preauricular keloid in conjunction with surgical resection.

Stem cells, niches and scaffolds: Applications to burns and wound care

The importance of skin to survival, and the devastating physical and psychological consequences of scarring following reparative healing of extensive or difficult to heal human wounds, cannot be disputed. We discuss the significant challenges faced by patients and healthcare providers alike in treating these wounds. New state of the art technologies have provided remarkable insights into the role of skin stem and progenitor cells and their niches in maintaining skin homeostasis and in reparative wound healing. Based on this knowledge, we examine different approaches to repair extensive burn injury and chronic wounds, including full and split thickness skin grafts, temporising matrices and scaffolds, and composite cultured skin products. Notable developments include next generation skin substitutes to replace split thickness skin autografts and next generation gene editing coupled with cell therapies to treat genodermatoses. Further refinements are predicted with the advent of bioprinting technologies, and newly defined biomaterials and autologous cell sources that can be engineered to more accurately replicate human skin architecture, function and cosmesis. These advances will undoubtedly improve quality of life for patients with extensive burns and difficult to heal wounds.

Antimicrobial Peptides Secreted From Human Cryopreserved Viable Amniotic Membrane Contribute to its Antibacterial Activity

Chronic wounds remain a large problem in the field of medicine and are often associated with risk of infection and amputation. Recently, a commercially available human cryopreserved viable amniotic membrane (hCVAM) has been shown to effectively promote wound closure and reduce wound-related infections. A sprevious study indicates that hCVAM can inhibit the growth of bacteria associated with chronic wounds. In the present study, we investigated the mechanism of hCVAM antimicrobial activity. Our data demonstrate that antimicrobial activities against common pathogens in chronic wounds such as P.aeruginosa, S.aureus and Methicillin-resistant S.aureus (MRSA) are mediated via the secretion of soluble factors by viable cells in hCVAM and that these factors are proteins in nature. Further, we show that genes for antimicrobial peptides (AMPs) including human beta-defensins (HBDs) are expressed by hCVAM and that expression levels positively correlate with antimicrobial activity of hCVAM. At the protein level, our data indicate that HBD2 and HBD3 are secreted by hCVAM and directly contribute to its activity against P. aeruginosa. These data provide evidence that soluble factors including AMPs are hCVAM antimicrobial agents and are consistent with a role for AMPs in mediating antimicrobial properties of the membrane.