A mechanistic evaluation of the angiogenic properties of a dehydrated amnion chorion membrane in vitro and in vivo

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.

Dehydrated Amnion Chorion Membrane versus standard of care for diabetic foot ulcers: a randomised controlled trial

OBJECTIVE

Diabetic foot ulcers (DFUs) continue to challenge wound care practitioners. This prospective, multicentre, randomised controlled trial (RCT) evaluated the effectiveness of a dehydrated Amnion Chorion Membrane (dACM) (Organogenesis Inc., US) versus standard of care (SoC) alone in complex DFUs in a challenging patient population.

METHOD

Subjects with a DFU extending into dermis, subcutaneous tissue, tendon, capsule, bone or joint were enrolled in a 12-week trial. They were allocated equally to two treatment groups: dACM (plus SoC); or SoC alone. The primary endpoint was frequency of wound closure determined by a Cox analysis that adjusted for duration and wound area. Kaplan-Meier analysis was used to determine median time to complete wound closure (CWC).

RESULTS

The cohort comprised 218 patients, and these were split equally between the two treatment groups with 109 patients in each. A Cox analysis showed that the estimated frequency of wound closure for the dACM plus SoC group was statistically superior to the SoC alone group at week 4 (12% versus 8%), week 6 (22% versus 11%), week 8 (31% versus 21%), week 10 (42% versus 27%) and week 12 (50% versus 35%), respectively (p=0.04). The computed hazard ratio (1.48 (confidence interval: 0.95, 2.29) showed a 48% greater probability of wound closure in favour of the dACM group. Median time to wound closure for dACM-treated ulcers was 84 days compared to 'not achieved' in the SoC-treated group (i.e., ≥50% of SoC-treated DFUs failed to heal by week 12; p=0.04).

CONCLUSION

In an adequately powered DFU RCT, dACM increased the frequency, decreased the median time, and improved the probability of CWC when compared with SoC alone. dACM demonstrated beneficial effects in DFUs in a complex patient population.

DECLARATION OF INTEREST

This study was funded by Organogenesis Inc., US. JC serves as a consultant and speaker for Organogenesis. RDD serves as a speaker for Organogenesis. OMA and MLS serve as consultants for Organogenesis. The authors have no other conflicts of interest to declare.

Dehydrated human amnion/chorion membrane allograft with spongy layer to significantly improve the outcome of chronic non-healing wounds

We investigated the healing effect of a new dehydrated amnion/chorion membrane with a spongy layer over a 30-month period in 32 patients with 53 chronic non-healing wounds of different aetiologies. Wounds with <40% surface reduction after 4 weeks of best wound treatment underwent weekly allograft application by a certified wound specialist based on national guidelines and a standardised protocol until complete healing or definite treatment interruption. The main outcome measure was the percentage of wound surface reduction from baseline calculated using digital planimetry follow-up photographs. Overall, 38 (71.7%) wounds presented a favourable outcome (70%-100% area reduction), with 35 (66%) completely healing over a median time of 77 days (range 29-350 days). Favourable outcomes were observed in 75% of traumatic wounds, surgical wounds, venous leg ulcers and pressure injuries, as well as in 50% of ischaemic wounds. Wounds being present <12 months were significantly more likely to have a favourable outcome than more long-standing wounds (χ2  = 7.799; p = 0.005; OR = 3.378; 95% CI, 1.410-8.092). Thus, treatment with dehydrated amnion/chorion membrane with a spongy layer improves the outcome of non-healing wounds of different aetiologies and, therefore, has to be considered early in the management of refractory wounds.

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.

Placental-Derived Biomaterials and Their Application to Wound Healing: A Review

Chronic wounds are associated with considerable patient morbidity and present a significant economic burden to the healthcare system. Often, chronic wounds are in a state of persistent inflammation and unable to progress to the next phase of wound healing. Placental-derived biomaterials are recognized for their biocompatibility, biodegradability, angiogenic, anti-inflammatory, antimicrobial, antifibrotic, immunomodulatory, and immune privileged properties. As such, placental-derived biomaterials have been used in wound management for more than a century. Placental-derived scaffolds are composed of extracellular matrix (ECM) that can mimic the native tissue, creating a reparative environment to promote ECM remodeling, cell migration, proliferation, and differentiation. Reliable evidence exists throughout the literature to support the safety and effectiveness of placental-derived biomaterials in wound healing. However, differences in source (i.e., anatomical regions of the placenta), preservation techniques, decellularization status, design, and clinical application have not been fully evaluated. This review provides an overview of wound healing and placental-derived biomaterials, summarizes the clinical results of placental-derived scaffolds in wound healing, and suggests directions for future work.

Protecting human amnion and chorion matrices during processing: Performance enhancement in a diabetic mouse model and human co-culture system

Recent evidence suggests that protecting human amnion and chorion matrices (HACM) during processing enhances the performance of HACM for wound repair and tissue regeneration. We utilised a diabetic (db/db) delayed wound healing mouse model. Treatment of db/db full-thickness excisional wounds with HACM, processed with a polyampholyte preservative accentuated the proliferative phase of wound healing that decreased the time necessary to heal wounds. Polyampholyte protection improved the preservation of growth factors and cytokines during room temperature storage following E-beam sterilisation and improved its function in wound healing applications. Our findings indicate protected HACM tissue up-regulated MIP2, NF-kB, TNF-α, KI-67, and Arg1 (0.6-fold to 1.5-fold) but those changes were not statistically significant. Immunofluorescent assessment identifying cell activity illustrated an induction of the proliferative phase of wound healing and a switch from an inflammatory macrophage phenotype (M1) to a pro-regenerative macrophage phenotype (M2a). Genomic profiling of 282 genes was performed using Nanostring from co-cultures of human macrophages and fibroblasts. The polyampholyte + HACM-treated group, compared with the HACM or polyampholyte alone groups, had a statistically significant up-regulation (32-368 fold) of 12 genes primarily involved in macrophage plasticity including CLC7, CD209, CD36, HSD11B1, ICAM1, IL1RN, IL3RA, ITGAX, LSP1, and PLXDC2 (adj. p-value < 0.05). The polyampholyte alone group demonstrated statistically significant down-regulation of four genes ADRA2, COL7A1, CSF3, and PTGS2 (adj. p < 0.05). The HACM alone group up-regulated four genes ATG14, CXCL11, DNMT3A, and THBD, but the results were not statistically significant. Biomechanical measurements indicated that wounds treated with polyampholyte-protected HACM had more tensile integrity compared with wounds treated with HACM alone. These findings indicate that better protection of HACM during processing stabilises the HACM matrix, which may lead to improved wound healing outcomes.

Biological properties and surgical applications of the human amniotic membrane

The amniotic membrane (AM) is the inner part of the placenta. It has been used therapeutically for the last century. The biological proprieties of AM include immunomodulatory, anti-scarring, anti-microbial, pro or anti-angiogenic (surface dependent), and tissue growth promotion. Because of these, AM is a functional tissue for the treatment of different pathologies. The AM is today part of the treatment for various conditions such as wounds, ulcers, burns, adhesions, and skin injury, among others, with surgical resolution. This review focuses on the current surgical areas, including gynecology, plastic surgery, gastrointestinal, traumatology, neurosurgery, and ophthalmology, among others, that use AM as a therapeutic option to increase the success rate of surgical procedures. Currently there are articles describing the mechanisms of action of AM, some therapeutic implications and the use in surgeries of specific surgical areas, this prevents knowing the therapeutic response of AM when used in surgeries of different organs or tissues. Therefore, we described the use of AM in various surgical specialties along with the mechanisms of action, helping to improve the understanding of the therapeutic targets and achieving an adequate perspective of the surgical utility of AM with a particular emphasis on regenerative medicine.

Standardized reporting of amnion and amnion/chorion allograft data for wound care

Background

The favorable biological and mechanical properties of the most common components of the placenta, the amnion and chorion, have been explored for regenerative medical indications. The use of the combination of amnion and chorion has also become very popular. But, published data from placental tissues in their final, useable form is lacking. During treatment with membrane product, the tissue is usually sterile, intact and laid on a wound or treatment area. The factors available to the treatment area from the applied product need to be elucidated and presented in a relatable form. Current reporting for eluted growth factor results are typically expressed per milliliter, which is not informative with respect to the area of tissue covered by the actual membrane and may differ among techniques.

Methods

To address this inconsistency, amnion or amnion/chorion were isolated from human placentas and processed by a proprietary procedure. The final dry, sterilized product was evaluated for structural components and growth factor elution. Growth factors were quantified by multiplex panels and ELISAs and the values normalized to specific area and elution volume of finished product. This information allows extrapolation to all membrane sizes and affords cross‐study comparisons.

Results

Analysis of membrane supernatants show that dehydrated, sterilized amnion and amnion/chorion elute factors that are conducive to wound healing, which are available to recipient tissues. Importantly, these measurable factors eluted from dehydrated, sterilized membranes can be reported as a function of available factors per square centimeter of tissue.

Conclusions

The standardized characterization of dehydrated, sterilized amnion and amnion/chorion as delivered to recipient tissues permits understanding and comparison of the products across various graft sizes, types, and eluate volumes. Further, reporting this data as a function of cm² of dehydrated tissue allows extrapolation by independent scientists and clinicians.

A decellularized flowable placental connective tissue matrix supports cellular functions of human tenocytes in vitro

Purpose

Injectable connective tissue matrices (CTMs) may promote tendon healing, given their minimally invasive properties, structural and biochemical extracellular matrix components, and capacity to fill irregular spaces. The purpose of this study is to evaluate the effects of placental CTMs on the cellular activities of human tenocytes. Decellularization, the removal of cells, cell fragments, and DNA from CTMs, has been shown to reduce the host’s inflammatory response. Therefore, the authors hypothesize that a decellularized CTM will provide a more cell-friendly matrix to support tenocyte functions.

Methods

Three human placental CTMs were selected for comparison: AmnioFill® (A-CTM), a minimally manipulated, non-viable cellular particulate, BioRenew™ (B-CTM), a liquid matrix, and Interfyl® (I-CTM), a decellularized flowable particulate. Adhesion and proliferation were evaluated using cell viability assays and tenocyte migration using a transwell migration assay. Gene expression of tenocyte markers, cytokines, growth factors, and matrix metalloprotease (MMP) in tenocytes were assessed using quantitative polymerase chain reaction.

Results

Although A-CTM supported more tenocyte adhesion, I-CTM promoted significantly more tenocyte proliferation compared with A-CTM and B-CTM. Unlike A-CTM, tenocyte migration was higher in I-CTM than the control. The presence of I-CTM also prevented the loss of tenocyte phenotype, attenuated the expression of pro-inflammatory cytokines, growth factors, and MMP, and promoted the expression of antifibrotic growth factor, TGFβ3.

Conclusion

Compared with A-CTM and B-CTM, I-CTM interacted more favorably with human tenocytes in vitro. I-CTM supported tenocyte proliferation with reduced de-differentiation and attenuation of the inflammatory response, suggesting that I-CTM may support tendon healing and regeneration in vivo.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00509-4.

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.

Developing a pro-angiogenic placenta derived amniochorionic scaffold with two exposed basement membranes as substrates for cultivating endothelial cells

Decellularized and de-epithelialized placenta membranes have widely been used as scaffolds and grafts in tissue engineering and regenerative medicine. Exceptional pro-angiogenic and biomechanical properties and low immunogenicity have made the amniochorionic membrane a unique substrate which provides an enriched niche for cellular growth. Herein, an optimized combination of enzymatic solutions (based on streptokinase) with mechanical scrapping is used to remove the amniotic epithelium and chorion trophoblastic layer, which resulted in exposing the basement membranes of both sides without their separation and subsequent damages to the in-between spongy layer. Biomechanical and biodegradability properties, endothelial proliferation capacity, and in vivo pro-angiogenic capabilities of the substrate were also evaluated. Histological staining, immunohistochemistry (IHC) staining for collagen IV, and scanning electron microscope demonstrated that the underlying amniotic and chorionic basement membranes remained intact while the epithelial and trophoblastic layers were entirely removed without considerable damage to basement membranes. The biomechanical evaluation showed that the scaffold is suturable. Proliferation assay, real-time polymerase chain reaction for endothelial adhesion molecules, and IHC demonstrated that both side basement membranes could support the growth of endothelial cells without altering endothelial characteristics. The dorsal skinfold chamber animal model indicated that both side basement membranes could promote angiogenesis. This bi-sided substrate with two exposed surfaces for cultivating various cells would have potential applications in the skin, cardiac, vascularized composite allografts, and microvascular tissue engineering.

Dehydrated human amniotic membrane regulates tenocyte expression and angiogenesis in vitro: Implications for a therapeutic treatment of tendinopathy

Tendon injuries are among the most common ailments of the musculoskeletal system. Prolonged inflammation and persistent vasculature are common complications associated with poor healing. Damaged tendon, replaced with scar tissue, never completely regains the native structural or biomechanical properties. This study evaluated the effects of micronized dehydrated human amnion/chorion membrane (μdHACM) on the inflammatory environment and hypervascularity associated with tendinopathy. Stimulation of human tenocytes with interleukin‐1 beta (IL1β) induced the expression of inflammatory and catabolic markers, resulting in secretion of active MMPs and type 3 collagen that is associated with a degenerative phenotype. Treatment with μdHACM diminished the effects of IL1β, reducing the expression of inflammatory genes, proteases, and extracellular matrix components, and decreasing the presence of active MMP and type 3 collagen. Additionally, a co‐culture model was developed to evaluate the effects of μdHACM on angiogenesis associated with tendinopathy. Micronized dHACM differentially regulated angiogenesis depending upon the cellular environment in which it was placed. This phenomenon can be explained in part through the detection of both angiogenic protagonists and antagonists in μdHACM. Observations from this study identify a mechanism by which μdHACM regulates inflammatory processes and angiogenesis in vitro, two key pathways implicated in tendinopathic injuries.

Uncovering the Depths of the Human Proteome: Antibody-based Technologies for Ultrasensitive Multiplexed Protein Detection and Quantification

Probing the human proteome in tissues and biofluids such as plasma is attractive for biomarker and drug target discovery. Recent breakthroughs in multiplex, antibody-based, proteomics technologies now enable the simultaneous quantification of thousands of proteins at as low as sub fg/ml concentrations with remarkable dynamic ranges of up to 10-log. We herein provide a comprehensive guide to the methodologies, performance, technical comparisons, advantages, and disadvantages of established and emerging technologies for the multiplexed ultrasensitive measurement of proteins. Gaining holistic knowledge on these innovations is crucial for choosing the right multiplexed proteomics tool for applications at hand to critically complement traditional proteomics methods. This can bring researchers closer than ever before to elucidating the intricate inner workings and cross talk that spans multitude of proteins in disease mechanisms.

Chorion and amnion/chorion membranes in oral and periodontal surgery: A systematic review

The aim of this study was to perform a systematic review on the clinical applications where chorion membrane (CM) and amnion/chorion membrane (ACM) were used for oral tissue regeneration procedures. Selection of articles was carried out by two evaluators in Pubmed and Scopus databases, and Outcomes (PICO) method was used to select the relevant articles. Clinical studies reporting the use of CM or ACM for oral soft and hard tissue regeneration were included. The research involved 21 studies conducted on 375 human patients. Seven clinical applications of CM and ACM in oral and periodontal surgery were identified: gingival recession treatment, intrabony and furcation defect treatment, alveolar ridge preservation, keratinized gum width augmentation around dental implants, maxillary sinus membrane repair, and large bone defect reconstruction. CM and ACM were compared to negative controls (conventional surgeries without membrane) or to the following materials: collagen membranes, dense polytetrafluoroethylene membranes, platelet-rich fibrin membranes, amnion membranes, and to a bone substitute. Several studies support the use of CM and ACM as an efficient alternative to current techniques for periodontal and oral soft tissue regeneration procedures. However, further studies are necessary to increase the level of evidence and especially to demonstrate their role for bone regeneration.

A prospective clinical trial evaluating changes in the wound microenvironment in patients with chronic venous leg ulcers treated with a hypothermically stored amniotic membrane

Amniotic tissues have been long utilised to treat chronic wounds; however, there are few studies evaluating how the wound microenvironment responds to these therapies. The goal of this study was to evaluate the changes in wounds treated with a hypothermically stored amniotic membrane (HSAM). In this prospective single‐arm study, 15 female patients with venous leg ulcers were treated with HSAM from male donors and standard of care for 12 weeks. Over the course of the study, wound exudate was collected and evaluated using proteomic microarrays. Biopsies were collected during the course of treatment to detect the presence of HSAM tissue. By 4 weeks, 60% of subjects achieved 50% or greater reduction in wound size, and by 12 weeks, 53% of subjects achieved 100% re‐epithelialization. HSAM DNA was detected in 20% of biopsies as determined by the detection TSPY4, indicating HSAM was no longer present within the wound bed approximately 7 days from the last treatment for the majority of wounds. Proteomic analysis of wound exudate found that wounds on a healing trajectory had significantly higher levels of MMP‐10, MMP‐7, and TIMP‐4 and significantly lower levels of CX3CL1, FLT‐3 L, IL‐1ra, IL‐1a, IL‐9, IL‐2, IL‐3, MCP‐1, and TNF‐b compared with other wounds.

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.