Dehydrated Human Amniotic Membrane Inhibits Myofibroblast Contraction through the Regulation of the TGFβ‒SMAD Pathway In Vitro

Contraction of a Giant Epiretinal Human Amniotic Membrane Patch Used to Manage a Highly Myopic Retinal Detachment Associated With Multiple Breaks

A 64-year-old highly myopic woman with macular hole retinal detachment (MHRD) in her left eye underwent vitrectomy, internal limiting membrane (ILM) peeling, and epiretinal implantation of a 4-mm diameter human amniotic membrane (hAM) patch. One month later, she developed a bullous superior RD in her right eye, associated with a huge MH and multiple posterior breaks. Vitrectomy and ILM peeling were combined with a 15-mm epiretinal hAM patch implantation. One year later, both eyes showed successful MH closure, but the right eye developed an eccentric hAM patch contraction starting 6 months postoperatively, causing a localized stable superonasal RD. [Ophthalmic Surg Lasers Imaging Retina 2024;55:XX-XX.].

Human amniotic membrane modulates collagen production and deposition in vitro

Pathological fibrosis is a significant complication of surgical procedures resulting from the accumulation of excess collagen at the site of repair which can compromise the tissue architecture and severely impede the function of the affected tissue. Few prophylactic treatments exist to counteract this process; however, the use of amniotic membrane allografts has demonstrated promising clinical outcomes. This study aimed to identify the underlying mechanism of action by utilizing relevant models that accurately represent the pathophysiology of the disease state. This study employed a pro-fibrotic in vitro system using TGFβ1 stimulation and macromolecular crowding techniques to evaluate the mechanism by which amniotic membrane allografts regulate collagen biosynthesis and deposition. Following treatment with dehydrated human amnion chorion membrane (DHACM), subsequent RNA sequencing and functional enrichment with Reactome pathway analysis indicated that amniotic membranes are indeed capable of regulating genes associated with the composition and function of the extracellular matrix. Furthermore, macromolecular crowding was used in vitro to expand the evaluation to include both the effects of DHACM and a lyophilized human amnion/chorion membrane (LHACM). DHACM and LHACM regulate the TGFβ pathway and myofibroblast differentiation. Additionally, both DHACM and LHACM modulate the production, secretion, and deposition of collagen type I, a primary target for pathological fibrosis. These observations support the hypothesis that amniotic membranes may interrupt pathological fibrosis by regulating collagen biosynthesis and associated pathways.

PURION® processed human amnion chorion membrane allografts retain material and biological properties supportive of soft tissue repair

The reparative properties of amniotic membrane allografts are well-suited for a broad spectrum of specialties. Further enhancement of their utility can be achieved by designing to the needs of each application through the development of novel processing techniques and tissue configurations. As such, this study evaluated the material characteristics and biological 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). LHACM is thicker; therefore, its handling properties are ideal for deep, soft tissue deficits; whereas DHACM is more similar to a film-like overlay and may be used for shallow defects or surgical on-lays. Characterization of the similarities and differences between LHACM and DHACM was conducted through a series of in vitro and in vivo studies relevant to the healing cascade. Compositional analysis was performed through histological staining along with assessment of barrier membrane properties through equilibrium dialysis. In vitro cellular response was assessed in fibroblasts and endothelial cells using cell proliferation, migration, and metabolic assays. The in vivo cellular response was assessed in an athymic nude mouse subcutaneous implantation model. The results indicated the PURION® process preserved the native membrane structure, nonviable cells and collagen distributed in the individual layers of both products. Although, LHACM is thicker than DHACM, a similar composition of growth factors, cytokines, chemokines and proteases is retained and consequently elicit comparable in vitro and in vivo cellular responses. In culture, both treatments behaved as potent mitogens, chemoattractants and stimulants, which translated to the promotion of cellular infiltration, neocollagen deposition and angiogenesis in a murine model. PURION® processed LHACM and DHACM differ in physical properties but possess similar in vitro and in vivo activities highlighting the impact of processing method on the versatility of clinical use of amniotic membrane allografts.

Role of allogeneic placental tissues in penile inversion vaginoplasty

Background

The role of allogeneic placental tissue (APT) in genital gender-affirming surgery (GAS) is not well understood. Penile inversion vaginoplasty (PIV), the most common genital GAS, often results in tissue healing- or wound-related complications, including scarring and neovaginal stenosis. Surgical reoperation and revision vaginoplasty are common. The aim of this study was to evaluate the contribution of APT to postoperative outcomes in PIV.

Methods

The authors performed a retrospective analysis of consecutive adult patients undergoing primary PIV during a 6-year period (September 1, 2014 to September 1, 2020). Subjects receiving intraoperative application of an APT biomaterial were compared to those undergoing primary PIV without APT. Postoperative outcomes-including wound healing morbidity and reoperation-were compared between groups. Short- and long-term complications were classified using Clavien-Dindo.

Results

A total of 182 primary PIV cases were reviewed (115 conventional PIV; 67 PIV-APT). The postoperative follow-up time for the population averaged 12.7 months. All-cause and wound related complications were significantly lower amongst PIV-APT patients when compared to conventional PIV (P=0.002 and P=0.004, respectively). The rate of long-term complications was significantly lower in PIV-APT subjects: prolonged pain (P=0.001), prolonged swelling (P=0.047), and neovaginal stenosis (P<0.001). The PIV-APT group required significantly less reoperation for vaginal depth enhancement (P=0.007).

Conclusions

Though its use in urogenital reconstruction has been limited, this study indicates that the placement of APT during PIV significantly lowered the risk of complications associated with poor wound healing. This supports a novel use for placental tissues in reducing complications in genital GAS.

Application of Amniotic Membrane in Skin Regeneration

Amniotic membrane (AM) is an avascular structure composed of three different layers, which contain collagen, extracellular matrix, and biologically active cells (stem cells). Collagen, a naturally occurring matrix polymer, provides the structural matrix/strength of the amniotic membrane. Tissue remodeling is regulated by growth factors, cytokines, chemokines, and other regulatory molecules produced by endogenous cells within AM. Therefore, AM is considered an attractive skin-regenerating agent. This review discusses the application of AM in skin regeneration, including its preparation for application to the skin and its mechanisms of therapeutic healing in the skin. This review involved collecting research articles that have been published in several databases, including Google Scholar, PubMed, Science Direct, and Scopus. The search was conducted by using the keywords ‘amniotic membrane skin’, ‘amniotic membrane wound healing’, ‘amniotic membrane burn’, ‘amniotic membrane urethral defects’, ‘amniotic membrane junctional epidermolysis bullosa’, and ‘amniotic membrane calciphylaxis’. Ultimately, 87 articles are discussed in this review. Overall, AM has various activities that help in the regeneration and repair of damaged skin.

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.

Industry updates from the field of stem cell research and regenerative medicine in June 2021

The latest developments in the field of stem cell research and regenerative medicine compiled from publicly available information and press releases from nonacademic institutions in June 2021.