Extract of fetal membrane would inhibit thrombosis and hemolysis

Receptors that bind to PEDF and their therapeutic roles in retinal diseases

Retinal neovascular, neurodegenerative, and inflammatory diseases represented by diabetic retinopathy are the main types of blinding eye disorders that continually cause the increased burden worldwide. Pigment epithelium-derived factor (PEDF) is an endogenous factor with multiple effects including neurotrophic activity, anti-angiogenesis, anti-tumorigenesis, and anti-inflammatory activity. PEDF activity depends on the interaction with the proteins on the cell surface. At present, seven independent receptors, including adipose triglyceride lipase, laminin receptor, lipoprotein receptor-related protein, plexin domain-containing 1, plexin domain-containing 2, F1-ATP synthase, and vascular endothelial growth factor receptor 2, have been demonstrated and confirmed to be high affinity receptors for PEDF. Understanding the interactions between PEDF and PEDF receptors, their roles in normal cellular metabolism and the response the initiate in disease will be accommodating for elucidating the ways in which inflammation, angiogenesis, and neurodegeneration exacerbate disease pathology. In this review, we firstly introduce PEDF receptors comprehensively, focusing particularly on their expression pattern, ligands, related diseases, and signal transduction pathways, respectively. We also discuss the interactive ways of PEDF and receptors to expand the prospective understanding of PEDF receptors in the diagnosis and treatment of retinal diseases.

Development of a decellularized human amniotic membrane-based electrospun vascular graft capable of rapid remodeling for small-diameter vascular applications

The performance of small-diameter vascular grafts adapted to vascular replacement is commonly hindered by stenosis. To address this issue, a graft featuring rapid remodeling with degradation is warranted. In this work, a 1.8-mm-diameter graft was constructed by fabricating a decellularized human amniotic membrane (HAM) with polycaprolactone (PCL)/silk fibroin (SF) around it through electrospinning, namely, an HPS graft, and applied in a rat aortic grafting model for comparison to a decellularized porcine small intestinal submucosa (SIS)-integrated PCL/SF (SPS) graft and an autologous aorta. In vitro studies demonstrated that HAM provided a bioactive milieu for rapid endothelial cell proliferation and resisting fibroblast-induced collagen secretion. PCL/SF provides a biocompatible microenvironment for cellular infiltration with mechanical properties resembling those of the rat aorta. In vivo studies showed that the HPS graft induced functional endothelialization more rapidly, along with less intensive ECM deposition than the SPS graft upon the histologically weaker inflammatory response and foreign body reaction 4 weeks after implantation, and maintained patency by progressively stabilizing the remodeling structure approximating the native counterparts over 24 weeks. The bioengineered graft expands the applicability of allogeneic matrices with degradable electrospun polymers for long-term in situ vascular applications. STATEMENT OF SIGNIFICANCE: An orchestrated remodeling of the vascular graft, featuring rapid endothelialization and resisting extracellular matrix (ECM) deposition on the luminal surface, with a mechanically stable structure, is requisite for long-term vascular patency. Nevertheless, off-the-shelf grafts might not fulfil the criteria under abdominal aortic pressure. Herein, we fabricated a 1.8-mm-diameter vascular graft through the integration of a decellularized human amniotic membrane (HAM) with electrospun polycaprolactone (PCL)/silk fibroin (SF). In a rat aortic grafting model, the graft is capable of rapid endothelialization and resisting collagen deposition and provides a native-like mechanical structure for stabilizing the remodeling process towards that of the native aorta. This bioengineered graft has potential for small-diameter vascular regeneration, and provides advanced strategies to facilitate full-remodeling tissue applications.

Human placenta-derived amniotic epithelial cells as a new therapeutic hope for COVID-19-associated acute respiratory distress syndrome (ARDS) and systemic inflammation

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has become in the spotlight regarding the serious early and late complications, including acute respiratory distress syndrome (ARDS), systemic inflammation, multi-organ failure and death. Although many preventive and therapeutic approaches have been suggested for ameliorating complications of COVID-19, emerging new resistant viral variants has called the efficacy of current therapeutic approaches into question. Besides, recent reports on the late and chronic complications of COVID-19, including organ fibrosis, emphasize a need for a multi-aspect therapeutic method that could control various COVID-19 consequences. Human amniotic epithelial cells (hAECs), a group of placenta-derived amniotic membrane resident stem cells, possess considerable therapeutic features that bring them up as a proposed therapeutic option for COVID-19. These cells display immunomodulatory effects in different organs that could reduce the adverse consequences of immune system hyper-reaction against SARS-CoV-2. Besides, hAECs would participate in alveolar fluid clearance, renin–angiotensin–aldosterone system regulation, and regeneration of damaged organs. hAECs could also prevent thrombotic events, which is a serious complication of COVID-19. This review focuses on the proposed early and late therapeutic mechanisms of hAECs and their exosomes to the injured organs. It also discusses the possible application of preconditioned and genetically modified hAECs as well as their promising role as a drug delivery system in COVID-19. Moreover, the recent advances in the pre-clinical and clinical application of hAECs and their exosomes as an optimistic therapeutic hope in COVID-19 have been reviewed.

Management of submacular massive haemorrhage in age-related macular degeneration: comparison between subretinal transplant of human amniotic membrane and subretinal injection of tissue plasminogen activator

PURPOSE

Macular neovascularization (MNV) can complicate age-related macular degeneration (AMD) and lead to severe visual acuity reduction. Massive submacular haemorrhage (SMH) is a sight-threatening complication of MNV and a challenge in the management of complications related to MNV in AMD since the effects of anti-vascular endothelial growth factor treatment alone are insufficient. Here, we evaluate the different postoperative outcomes of patients affected by MNV complicated by SMH that underwent subretinal implant of human amniotic membrane (hAM) or subretinal injection of tissue plasminogen activator (tPA).

METHODS

This is a retrospective, consecutive, comparative, non-randomized interventional study. We included 44 eyes of 44 patients affected by AMD complicated by MNV and SMH. Twenty-two eyes underwent a pars plana vitrectomy (PPV), SMH and neovascular membrane removal, with a subretinal implant of hAM and silicone oil, and 22 eyes underwent PPV, subretinal injection of tPA, and 20% sulphur hexafluoride. The primary study outcome was visual acuity improvement. Secondary outcomes were postoperative complications, and MNV recurrence and optical coherence tomography (OCT)-Angiography parameters correlated with best-corrected visual acuity (BCVA).

RESULTS

Mean preoperative BCVA was 1.9 logarithm of the minimal angle of resolution (logMAR) in the amniotic membrane-group and 2 logMAR in the tPA-group. The mean final BCVA values were 1.25 and 1.4 logMAR, respectively, with a statistically significant difference. Optical coherence tomography (OCT)-Angiography scan was be used to evaluate the retinal vascularization in the treated eye.

CONCLUSION

Both techniques report similar VA improvements and postoperative complications. However, transplantation of hAM seems to have a significant benefit in inhibiting MNV recurrence.

Effects of histone H4 hyperacetylation on inhibiting MMP2 and MMP9 in human amniotic epithelial cells and in premature rupture of fetal membranes

Histone modification is closely associated with several diseases. The aim of the current study was to investigate the associations among histone acetylation, matrix metalloproteinases (MMPs) and premature rupture of membranes (PROM) during pregnancy. A total of 180 puerperants were divided into three groups: i) Preterm-PROM (PPROM), ii) term-PROM (TPROM) and iii) full-term labor (FTL). Enzyme-linked immunosorbent assay (ELISA) kits and western blotting were used to determine the protein concentrations of MMP2, MMP9, histone deacetylase (HDAC)1, HDAC2 and HDAC6, and the protein levels of histone H4 lysine (H4K)5 and H4K8 acetylation, respectively, in three types of fetal membranes. Additionally, human amniotic epithelial cells were used to determine the effects of the HDAC inhibitors droxinostat and chidamide on cell viability, histone acetylation and the levels of MMP2, MMP9, HDAC1, HDAC2 and HDAC6 in vitro, using the Cell Counting Kit-8 assay, western blotting and ELISA, respectively. Furthermore, the effects of droxinostat and chidamide on the invasion and migration abilities of human amniotic epithelial cells were investigated using transwell assays. In fetal membranes, the activities of MMP2 and MMP9 increased in PPROM, but decreased in TPROM. Further, the expression of HDAC1 was decreased and histone hyperacetylation was increased in both PPROM and TRPOM. In vitro experiments revealed that 5 µM droxinostat and 0.5 µM chidamide selectively decreased the level of HDAC and induced acetylation of H4K5 and H4K8. Additionally, the aforementioned HDAC inhibitors reduced human amniotic epithelial cell viability, invasion and migration, and decreased the expression levels of MMP2 and MMP9. The current study revealed a high expression level of MMP2 and MMP9 in PPROM compared with TPROM and FL tissue, which was in accordance with previously published studies. Furthermore, the in vitro tests performed in the current study revealed the effect of histone H4 hyperacetylation on inhibiting MMP2 and MMP9 levels in vitro was similar to that observed in TPROM. The results obtained in the current study may be used as a theoretical guide for clinical treatment of premature rupture of membranes.

Insights on the Human Amniotic Membrane in Clinical Practice with a Focus on the New Applications in Retinal Surgery

Recently, the use of the human amniotic membrane (hAM) has been extended to treat retinal disorders such as refractory macular holes, retinal breaks and dry and wet age-related macular degeneration. Not only the hAM has proved to be an excellent tool for repairing retinal tissue, but it has also shown a promising regeneration potential. This review aims to highlight the novel use of the hAM in treating retinal diseases. Although the hAM has been used in the ocular anterior segment reconstruction for more than 60 years, in the last 2 years, we have found in literature articles showing the use of the hAM in the retinal surgery field with interesting results in terms of tissue healing and photoreceptor regeneration.

Applications of the Amniotic Membrane in Vitreoretinal Surgery

Recently, the use of the human amniotic membrane (hAM) has been extended to treat retinal disorders, such as macular holes that failed to close and retinal tears. The hAM has demonstrated the induction of a recovery process of the external retinal layers involving the external limiting membrane (ELM) and the ellipsoid zone (EZ). After that, the application of the hAM for retinal pathologies was extended to large macular tears, high myopic retinal detachment associated with MH, paravascular tears, serous macular detachment associated with optic pit, complicated retinal detachment and advanced age-related macular degeneration (AMD). The hAM has shown a potential in repairing retinal tissue through a regeneration process. This review aims to highlight the use of the hAM in various vitreo-retinal surgical fields, and to confront it with other cutting-edge surgical techniques used to treat challenging vitreo-retinal pathologies.

Human Amniotic Membrane Plug to Restore Age-Related Macular Degeneration Photoreceptor Damage

PURPOSE

Age-related macular degeneration (AMD) is the leading cause of legal blindness in adults 65 years of age and older. Choroidal neovascularization (CNV) can complicate AMD and lead to severe visual acuity reduction. Despite the several treatments available, if the retinal pigment epithelium is damaged, we have to cope with the impossibility of restoring acceptable visual acuity using only medical treatments.

DESIGN

Prospective, consecutive, interventional study.

PARTICIPANTS

Eleven patients affected by AMD, 6 patients affected by CNV, and 5 patients affected by geographic atrophy.

METHODS

All patients underwent a pars plana vitrectomy with subretinal implantation of human amniotic membrane (hAM) to induce photoreceptor regeneration and partial visual acuity restoration.

MAIN OUTCOME MEASURES

Primary study outcome was visual acuity improvement. Secondary outcomes were multimodal imaging results.

RESULTS

Mean preoperative best-corrected visual acuity (BCVA) was 20/2000 (2 logarithm of the minimum angle of resolution [logMAR]), and all the patients showed a BCVA of counting fingers or less. Mean final BCVA was 20/400 (1.31 logMAR), ranging from 20/2000 to 20/100 (2-0.7 logMAR). OCT angiography was used to measure retinal vascularization in the treated eye compared with the fellow eye. A high correlation between BCVA and deep vascular density was evidenced. Adaptive optics findings, obtained over the retinal area where the highest functionality was observed, were evaluated using microperimetry. The images showed possible photoreceptor presence over the hAM membrane.

CONCLUSIONS

This work supports the feasibility and safety of the hAM to promote partial retinal function restoration 6 months after surgery with visual acuity improvement. The advanced diagnostics help to understand the interaction between the hAM and photoreceptors and suggest that photoreceptor regeneration may occur.

A human Amniotic Membrane plug to manage high myopic macular hole associated with retinal detachment

OBJECTIVE

To assess the efficacy of the human amniotic membrane (hAM) to treat (HMMH) associated with retinal detachment (RD).

MATERIAL AND METHODS

Ten eyes of 10 patients with recurrent HMMH and RD, who had already undergone one or more pars plana vitrectomy (PPV), underwent a PPV with an hAM plug implanted in the macular hole. The initial five patients enrolled were tamponaded with (SO) while the subsequent five patients with 10% octafluoropropane (C₃ F₈ ). Silicon oil was removed in all five patients 2 months later. No statistical differences were reported between the two groups.

RESULTS

Final retinal reattachment was achieved in all the patients. BCVA improved from 1.73 logMAR to 0.94 logMAR after 6 months. No adverse events were registered during follow-up.

CONCLUSION

An hAM plug is an efficient substrate to manage HMMH associated with RD resulting in encouraging visual acuity recovery.

Vascular tissue engineering: Fabrication and characterization of acetylsalicylic acid-loaded electrospun scaffolds coated with amniotic membrane lysate

As the incidence of small-diameter vascular graft (SDVG) occlusion is considerably high, a great amount of research is focused on constructing a more biocompatible graft. The absence of a biocompatible surface in the lumen of the engineered grafts that can support confluent lining with endothelial cells (ECs) can cause thrombosis and graft failure. Blood clot formation is mainly because of the lack of an integrated endothelium. The most effective approach to combat this problem would be using natural extracellular matrix constituents as a mimic of endothelial basement membrane along with applying anticoagulant agents to provide local antithrombotic effects. In this study, we fabricated aligned and random electrospun poly-L-lactic acid (PLLA) scaffolds containing acetylsalicylic acid (ASA) as the anticoagulation agent and surface coated them with amniotic membrane (AM) lysate. Vascular scaffolds were structurally and mechanically characterized and assessed for cyto- and hemocompatibility and their ability to support endothelial differentiation was examined. All the scaffolds showed appropriate tensile strength as expected for vascular grafts. Lack of cytotoxicity, cellular attachment, growth, and infiltration were proved using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and scanning electron microscopy. The blood compatibilities of different scaffolds examined by in vitro hemolysis and blood coagulation assays elucidated the excellent hemocompatibility of our novel AM-coated ASA-loaded nanofibers. Drug-loaded scaffolds showed a sustained release profile of ASA in 7 days. AM-coated electrospun PLLA fibers showed enhanced cytocompatibility for human umbilical vein ECs, making a confluent endothelial-like lining. In addition, AM lysate-coated ASA-PLLA-aligned scaffold proved to support endothelial differentiation of Wharton's jelly-derived mesenchymal stem cells. Our results together indicated that AM lysate-coated ASA releasing scaffolds have promising potentials for development of a biocompatible SDVG.

Concise Review: Fetal Membranes in Regenerative Medicine: New Tricks from an Old Dog?

The clinical application of the fetal membranes dates back to nearly a century. Their use has ranged from superficial skin dressings to surgical wound closure. The applications of the fetal membranes are constantly evolving, and key to this is the uncovering of multiple populations of stem and stem-like cells, each with unique properties that can be exploited for regenerative medicine. In addition to pro-angiogenic and immunomodulatory properties of the stem and stem-like cells arising from the fetal membranes, the dehydrated and/or decellularized forms of the fetal membranes have been used to support the growth and function of other cells and tissues, including adipose-derived mesenchymal stem cells. This concise review explores the biological origin of the fetal membranes, a history of their use in medicine, and recent developments in the use of fetal membranes and their derived stem and stem-like cells in regenerative medicine. Stem Cells Translational Medicine 2017;6:1767-1776.

Amniotic membrane and its epithelial and mesenchymal stem cells as an appropriate source for skin tissue engineering and regenerative medicine

One of the main goals of tissue engineering and regenerative medicine is to develop skin substitutes for treating deep dermal and full thickness wounds. In this regard, both scaffold and cell source have a fundamental role to achieve exactly the same histological and physiological analog of skin. Amnion epithelial and mesenchymal cells possess the characteristics of pluripotent stem cells which have the capability to differentiate into all three germ layers and can be obtained without any ethical concern. Amniotic cells also produce different growth factors, angio-modulatory cytokines, anti-bacterial peptides and a wide range of anti-inflammatory agents which eventually cause acceleration in wound healing. In addition, amniotic membrane matrix exhibits characteristics of an ideal scaffold and skin substitute through various types of extracellular proteins such as collagens, laminins and fibronectins which serve as an anchor for cell attachment and proliferation, a bed for cell delivery and a reservoir of drugs and growth factors involved in wound healing process. Recently, isolation of amniotic cells exosomes, surface modification and cross-linking approaches, construction of amnion based nanocomposites and impregnation of amnion with nanoparticles, construction of amnion hydrogel and micronizing process promoted its properties for tissue engineering. In this manuscript, the recent progress was reviewed which approve that amnion-derived cells and matrix have potential to be involved in skin substitutes; an enriched cell containing scaffold which has a great capability to be translated into the clinic.

Induction of antimicrobial peptides secretion by IL-1β enhances human amniotic membrane for regenerative medicine

Due to antibacterial characteristic, amnion has been frequently used in different clinical situations. Developing an in vitro method to augment endogenous antibacterial ingredient of amniotic epithelial and mesenchymal stem cells is desirable for a higher efficacy of this promising biomaterial. In this study, epithelial or mesenchymal side dependent effect of amniotic membrane (AM) on antibacterial activity against some laboratory and clinical isolated strains was investigated by modified disk diffusion method and colony count assay. The effect of exposure to IL-1β in production and release of antibacterial ingredients was investigated by ELISA assay. The results showed that there is no significant difference between epithelial and mesenchymal sides of amnion in inhibition of bacterial growth. Although the results of disk diffusion showed that the AM inhibitory effect depends on bacterial genus and strain, colony count assay showed that the extract of AM inhibits all investigated bacterial strains. The exposure of AM to IL-1β leads to a higher level of antibacterial peptides secretion including elafin, HBD-2, HBD-3 and cathelicidic LL-37. Based on these results, amniotic cells possess antibacterial activity which can be augmented by inflammatory signal inducers; a process which make amnion and its epithelial and mesenchymal stem cells more suitable for tissue engineering and regenerative medicine.

The effect of cryopreservation on anti-cancer activity of human amniotic membrane

Human amniotic membrane (AM) is an appropriate candidate for treatment of cancer due to special properties, such as inhibition of angiogenesis and secretion of pro-apoptotic factors. This research was designed to evaluate the impact of cryopreservation on cancer cell death induction and anti-angiogenic properties of the AM. Cancer cells were treated with fresh and cryopreserved amniotic condition medium during 24 h and cancer cell viability was determined by MTT assay. To evaluate angiogenesis, the rat aorta ring assay was performed for both fresh and cryopreserved AM within 7 days. In addition, four anti-angiogenic factors Tissue Inhibitor of Matrix Metalloproteinase-1 and 2 (TIMP-1 and TIMP-2), Thrombospondin, and Endostatin were measured by ELISA assay before and after cryopreservation. The results showed that the viability of cultured cancer cells dose-dependently decreased after treatment with condition medium of fresh and cryopreserved tissue and no significant difference was observed between the fresh and cryopreserved AM. The results revealed that the amniotic epithelial stem cells inhibit the penetration of fibroblast-like cells and angiogenesis. Moreover, the penetration of fibroblast-like cells in both epithelial and mesenchymal sides of fresh and cryopreserved AM was observed after removing of epithelial cells. The cryopreservation procedure significantly decreased anti-angiogenic factors TIMP-1, TIMP-2, Thrombospondin, and Endostatin which shows that angio-modulatory property is not fully dependent on proteomic and metabolomic profiles of the AM. These promising results demonstrate that cancer cell death induction and anti-angiogenic properties of the AM were maintained within cryopreservation; a procedure which can circumvent limitations of the fresh AM.