Cell-Free Amniotic Fluid and Regenerative Medicine: Current Applications and Future Opportunities

Undenatured type II collagen for knee osteoarthritis

INTRODUCTION

Knee Osteoarthritis (OA) leads to significant pain and reduced function and affects patients' overall quality of life (QoL). Conservative modalities are the first line of management, resorting to surgery only if they fail. However, these modalities have limitations, and do not address the underlying cause of knee OA. The use of nutraceuticals, including native/undenatured type II collagen (UC-2), has evolved and shown promise in the conservative management of knee OA. This article highlights the mechanism of action, and qualitatively presents the pre-clinical, clinical and on-going scientific literature exploring the safety and efficacy of UC-2 for the management of knee OA.

METHODS

A search was performed using multiple databases (PubMed, Web of Science, Embase and Scopus) employing terms for UC-2 and Knee OA for articles published in English language, while adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. All pre-clinical and clinical studies utilizing UC-2 for knee OA were included. Studies not using UC-2 alone or not focusing on the management of knee OA were excluded.

RESULTS

Twelve studies (3 pre-clinical studies, 8 clinical studies and 1 study with both pre-clinical and clinical component) met our pre-defined search and inclusion criteria, and were included in this review.

DISCUSSION

UC-2 acts via a specific immune mediated mechanism, known as oral tolerance, which can lead to reduced inflammation and enhanced cartilage repair in the knee joint. In addition, administration of UC-2 (40 mg daily) is safe and efficacious in the short- and mid-term, reducing inflammation and pain, and improving function, range of motion (ROM) and overall QoL. Nonetheless, more adequately powered, prospective, multi-center, non-randomized and randomized controlled trials with longer follow-up are warranted to establish the long-term efficacy of UC-2 in knee OA patients and justify its routine clinical use.

Amniotic Fluid Reduces Liver Fibrosis By Attenuating Hepatic Stellate Cell Activation

Regardless of the source of injury or metabolic dysfunction, fibrosis is a frequent driver of liver pathology. Excessive liver fibrosis is caused by persistent activation of hepatic stellate cells (HSCs), which is defined by myofibroblast activation (MFA) and the epithelial-mesenchymal transition (EMT). Strategies to prevent or reverse this HSC phenotype will be critical for successful treatment of liver fibrosis. We have previously shown that full-term, cell-free human amniotic fluid (cfAF) inhibits MFA and EMT in fibroblasts in vitro. We hypothesize that cfAF treatment can attenuate HSC activation and limit liver fibrosis. We tested if cfAF could prevent liver fibrosis or HSC activation in murine models of liver damage, three-dimensional hepatic spheroids, and HSC cultures. Administering cfAF prevented weight loss and the extent of fibrosis in mice with chronic liver damage without stimulating deleterious immune responses. Gene expression profiling and immunostaining indicated that cfAF administration in carbon tetrachloride-treated mice reduced EMT- and MFA-related biomarker abundance and modulated transcript levels associated with liver metabolism, immune regulatory pathways, and cell signaling. cfAF treatment lowered MFA biomarker levels in a dose-dependent manner in hepatic spheroids exposed to ethanol. Treating HSCs with cfAF in vitro strongly repressed EMT. Multi-omics analyses revealed that it also attenuates TGFβ-induced MFA and inflammation-associated processes. Thus, cfAF treatment prevents liver fibrosis by safeguarding against persistent HSC activation. These findings suggest that cfAF may be a safe and effective therapy for reducing liver fibrosis and preventing the development of cirrhosis and/or hepatocellular carcinoma.

Harnessing the Anti-Inflammatory Effects of Perinatal Tissue Derived Therapies for the Treatment of Inflammatory Skin Diseases: A Comprehensive Review

Dealing with chronic inflammatory skin conditions like atopic dermatitis and psoriasis can be extremely difficult. Current treatments, such as topical corticosteroids, often have limitations and side effects. However, researchers have discovered that the placenta's remarkable properties may provide a breakthrough in effectively addressing these skin conditions. The placenta comprises three essential tissues: decidua, placental membrane, and umbilical cord. Placental derivatives have shown significant potential in treating psoriasis by reducing inflammatory cytokines and inhibiting keratinocyte proliferation. In the case of atopic dermatitis, umbilical cord stem cells have demonstrated anti-inflammatory effects by targeting critical factors and promoting anti-inflammatory cytokines. The scope of benefits associated with placental derivatives transcends these specific applications. They also potentially address other inflammatory skin diseases, such as vitiligo, by stimulating melanin production. Moreover, these derivatives have been leveraged in the treatment of pemphigus and epidermolysis bullosa (EB), showcasing potential as a wound dressing that could eliminate the necessity for painful dressing changes in EB patients. In summary, the integration of placental derivatives stands to revolutionize our approach to inflammatory skin conditions owing to their distinct properties and the prospective benefits they offer. This comprehensive review delves into the current applications of placental derivatives in addressing inflammatory skin diseases, presenting a novel treatment approach.

Analyzing exosomal miRNA profiles in tetralogy of fallot fetuses' amniotic fluid

Amniotic fluid (AF)-derived exosomal miRNA have been explored as potential contributors to the pathogenesis of Tetralogy of Fallot (TOF). This study aimed to investigate the expression profiles of AF-derived exosomal miRNAs and their potential contribution to TOF development. Exosomes were isolated from AF samples obtained from pregnant women carrying fetuses diagnosed with TOF. AF-derived exosomal miRNAs expression profiles were generated using the Agilent human miRNA Array V21.0, comparing 5 TOF samples with 5 healthy controls. Differential expression analysis identified 257 significantly dysregulated miRNAs in the TOF group. KEGG pathway enrichment analysis revealed that the predicted targets of these differentially expressed miRNAs were enriched in pathways associated with congenital disorders. Notably, 25 of these miRNAs were previously reported to be regulated by both Notch and Wnt signaling pathways, which are critical to heart development. Further investigation using mouse embryonal carcinoma P19 cells revealed that miR-10a-5p overexpression inhibited cardiomyogenic differentiation, as evidenced by the suppression of cardiomyocyte marker genes like TBX5. A dual-luciferase reporter assay confirmed TBX5 as a direct target of miR-10a-5p, suggesting a regulatory mechanism involving their interaction. In summary, our study demonstrates that miR-10a-5p may contribute to the pathogenesis of TOF by impairing cardiomyocyte differentiation through direct targeting of TBX5. These findings enhance our understanding of TOF and its molecular underpinnings.

Amniotic fluid-derived stem cells: potential factories of natural and mimetic strategies for congenital malformations

BACKGROUND

Mesenchymal stem cells (MSCs) derived from gestational tissues offer a promising avenue for prenatal intervention in congenital malformations although their application is hampered by concerns related to cellular plasticity and the need for invasive, high-risk surgical procedures. Here, we present naturally occurring exosomes (EXOs) isolated from amniotic fluid-derived MSCs (AF-MSCs) and their mimetic analogs (MIMs) as viable, reproducible, and stable alternatives. These nanovesicles present a minimally invasive therapeutic option, addressing the limitations of MSC-based treatments while retaining therapeutic efficacy.

METHODS

MIMs were generated from AF-MSCs by combining sequential filtration steps through filter membranes with different porosity and size exclusion chromatography columns. A physicochemical, structural, and molecular comparison was conducted with exosomes (EXOs) released from the same batch of cells. Additionally, their distribution patterns in female mice were evaluated following in vivo administration, along with an assessment of their safety profile throughout gestation in a mouse strain predisposed to neural tube defects (NTDs). The possibility to exploit both formulations as mRNA-therapeutics was explored by evaluating cell uptake in two different cell types(fibroblasts, and macrophages) and mRNA functionality overtime in an in vitro experimental setting as well as in an ex vivo, whole embryo culture using pregnant C57BL6 dams.

RESULTS

Molecular and physiochemical characterization showed no differences between EXOs and MIMs, with MIMs determining a threefold greater yield. Biodistribution patterns following intraperitoneal administration were comparable between the two particle types, with the uterus being among targeted organs. No toxic effects were observed in the dams during gestation, nor were there any malformations or significant differences in the number of viable versus dead fetuses detected. MIMs delivered a more intense and prolonged expression of mRNA encoding for green fluorescent protein in macrophages and fibroblasts. An ex-vivo whole embryo culture demonstrated that MIMs mainly accumulate at the level of the yolk sac, while EXOs reach the embryo.

CONCLUSIONS

The present data confirms the potential application of EXOs and MIMs as suitable tools for prevention and treatment of NTDs and proposes MIMs as prospective vehicles to prevent congenital malformations caused by in utero exposure to drugs.

Autologous Growth Factor-Rich Concentrate (GFC) Injection in Non-union of Fractures: A Quasi-experimental Study

INTRODUCTION

Non-union fractures represent a significant challenge in orthopedic practice, contributing to considerable morbidity and socioeconomic burden. Traditional treatments, such as autologous bone grafting, are effective but have limitations, including donor-site morbidity and limited tissue availability. Autologous peripheral blood-derived orthobiologics, including growth factor-rich concentrate (GFC), have emerged as a minimally invasive alternative, leveraging the body's natural healing mechanisms by concentrating and applying growth factors directly to the fracture site. This study evaluates the safety and efficacy of GFC injections in the treatment of non-union fractures.

MATERIALS AND METHODS

This quasi-experimental study included 17 patients with non-union fractures of various long bones, treated under fluoroscopic guidance with three doses of 5 mL GFC injections, administered 2 weeks apart at the non-union site. Demographic data, injury characteristics, and comorbid conditions were recorded. Growth factor levels were quantified via enzyme-linked immunosorbent assay (ELISA), and statistical analyses were conducted to explore associations between the amount of growth factors and treatment outcomes. Radiographic assessments and bony callus appearance were evaluated at the baseline and at 1-, 3-, and 6-month follow-up post-last injection.

RESULTS

No adverse effects were reported throughout the duration of the study. The majority of patients (82.4%) showed significant improvement, evidenced by enhanced bony callus formation and reduced non-union signs. No significant correlation was found between the specific growth factor levels and the clinical outcomes of non-union of fractures. However, the presence of comorbid conditions significantly influenced treatment efficacy, underscoring the importance of patient selection in clinical practice.

CONCLUSION

Administration of GFC injection is safe and potentially efficacious for the treatment of non-union fractures, offering an alternative to traditional surgical interventions. These results laid the foundation for prospective, adequately powered, randomized and non-randomized clinical studies with longer follow-up to further establish the efficacy of GFC in patients with non-union fractures. Moreover, formulation protocols need to be optimized while considering patient-specific variables, to ensure reproducibility and repeatability of outcomes from these studies.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43465-024-01278-1.

Extracellular vesicles from II trimester human amniotic fluid as paracrine conveyors counteracting oxidative stress

BACKGROUND

We previously demonstrated that the human amniotic fluid (hAF) from II trimester of gestation is a feasible source of stromal progenitors (human amniotic fluid stem cells, hAFSC), with significant paracrine potential for regenerative medicine. Extracellular vesicles (EVs) separated and concentrated from hAFSC secretome can deliver pro-survival, proliferative, anti-fibrotic and cardioprotective effects in preclinical models of skeletal and cardiac muscle injury. While hAFSC-EVs isolation can be significantly influenced by in vitro cell culture, here we profiled EVs directly concentrated from hAF as an alternative option and investigated their paracrine potential against oxidative stress.

METHODS

II trimester hAF samples were obtained as leftover material from prenatal diagnostic amniocentesis following written informed consent. EVs were separated by size exclusion chromatography and concentrated by ultracentrifugation. hAF-EVs were assessed by nanoparticle tracking analysis, transmission electron microscopy, Western Blot, and flow cytometry; their metabolic activity was evaluated by oximetric and luminometric analyses and their cargo profiled by proteomics and RNA sequencing. hAF-EV paracrine potential was tested in preclinical in vitro models of oxidative stress and dysfunction on murine C2C12 cells and on 3D human cardiac microtissue.

RESULTS

Our protocol resulted in a yield of 6.31 ± 0.98 × 109 EVs particles per hAF milliliter showing round cup-shaped morphology and 209.63 ± 6.10 nm average size, with relevant expression of CD81, CD63 and CD9 tetraspanin markers. hAF-EVs were enriched in CD133/1, CD326, CD24, CD29, and SSEA4 and able to produce ATP by oxygen consumption. While oxidative stress significantly reduced C2C12 survival, hAF-EV priming resulted in significant rescue of cell viability, with notable recovery of ATP synthesis and concomitant reduction of cell damage and lipid peroxidation activity. 3D human cardiac microtissues treated with hAF-EVs and experiencing H2O2 stress and TGFβ stimulation showed improved survival with a remarkable decrease in the onset of fibrosis.

CONCLUSIONS

Our results suggest that leftover samples of II trimester human amniotic fluid can represent a feasible source of EVs to counteract oxidative damage on target cells, thus offering a novel candidate therapeutic option to counteract skeletal and cardiac muscle injury.

Amniotic fluid-derived stem cells: potential factories of natural and mimetic strategies for congenital malformations

Background

Mesenchymal stem cells (MSCs) from gestational tissues represent promising strategies for in utero treatment of congenital malformations, but plasticity and required high-risk surgical procedures limit their use. Here we propose natural exosomes (EXOs) isolated from amniotic fluid-MSCs (AF-MSCs), and their mimetic counterparts (MIMs), as valid, stable, and minimally invasive therapeutic alternatives.

Methods

MIMs were generated from AF-MSCs by combining sequential filtration steps through filter membranes with different porosity and size exclusion chromatography columns. Physiochemical and molecular characterization was performed to compare them to EXOs released from the same number of cells. The possibility to exploit both formulations as mRNA-therapeutics was explored by evaluating cell uptake (using two different cell types, fibroblasts, and macrophages) and mRNA functionality overtime in an in vitro experimental setting as well as in an ex vivo, whole embryo culture using pregnant C57BL6 dams.

Results

Molecular and physiochemical characterization showed no differences between EXOs and MIMs, with MIMs determining a 3-fold greater yield. MIMs delivered a more intense and prolonged expression of mRNA encoding for green fluorescent protein (GFP) in macrophages and fibroblasts. An ex-vivo whole embryo culture demonstrated that MIMs mainly accumulate at the level of the yolk sac, while EXOs reach the embryo.

Conclusions

The present data confirms the potential application of EXOs for the prenatal repair of neural tube defects and proposes MIMs as prospective vehicles to prevent congenital malformations caused by in utero exposure to drugs.

Use of amniotic membrane in hard-to-heal wounds: a multicentre retrospective study

OBJECTIVE

Hard-to-heal (chronic) wounds negatively impact patients and are a source of significant strain on the healthcare system and economy. These wounds are often resistant to standard of care (SoC) wound healing approaches due to a diversity of underlying pathologies. Cellular, acellular, and matrix-like products, such as amniotic membranes (AM), are a potential solution to these challenges. A growing body of evidence suggests that AM may be useful for treatment-resistant wounds; however, limited information is available regarding the efficacy of dehydrated amniotic membrane (DHAM) on multi-aetiology, hard-to-heal wounds. Therefore, we analysed the efficacy of DHAM treatment in reducing the size of hard-to-heal diabetic and venous leg ulcers (VLUs) that had failed to improve after SoC-based treatments.

METHOD

In this multicentre retrospective study, we analysed wound size during clinic visits for patients being treated for either diabetic or VLUs. During each visit, the treatment consisted of debridement followed by application of DHAM. Each wound was measured after debridement and prior to DHAM application, and wound volumes over time or number of DHAM applications were compared.

RESULTS

A total of 18 wounds in 11 patients were analysed as part of this study. Wounds showed a significant reduction in volume after a single DHAM application, and a 50% reduction in wound size was observed after approximately two DHAM applications. These findings are consistent with reports investigating DHAM treatment of diabetic ulcers that were not necessarily resistant to treatment.

CONCLUSION

To our knowledge, this study is the first to directly compare the efficacy of standalone DHAM application to hard-to-heal diabetic and venous leg ulcers, and our findings indicate that DHAM is an effective intervention for resolving these types of wounds. This suggests that implementing this approach could lead to fewer clinic visits, cost savings and improved patient quality of life.

DECLARATION OF INTEREST

This research was supported in part by Merakris Therapeutics, US, and facilitated access to deidentified patient datasets, which may represent a perceived conflict of interest; however, the primary data analysis was performed by FSB who is unaffiliated with Merakris Therapeutics. TCB is a founder, employee of and shareholder in Merakris Therapeutics; WSF is a co-founder of, consultant for, and shareholder in Merakris Therapeutics, and was also supported by the National Institutes of Health National Center for Advancing Translational Sciences Clinical and Translational Science Awards Grant KL2 Scholars Program (KL2TR001441). The research was also supported through endowments to WSF from the University of Texas Medical Branch Mimmie and Hallie Smith Endowed Chair of Transplant Research and the John L Hern University Chair in Transplant Surgery.

Solving STODS-Surgical Temporary Ocular Discomfort Syndrome

The term STODS (Surgical Temporary Ocular Discomfort Syndrome) has been coined to describe the ocular surface perturbations induced by surgery. As one of the most important refractive elements of the eye, Guided Ocular Surface and Lid Disease (GOLD) optimization is fundamental to success in achieving refractive outcomes and mitigating STODS. Effective GOLD optimization and the prevention/treatment of STODS requires an understanding of the molecular, cellular, and anatomic factors that influence ocular surface microenvironment and the associated perturbations induced by surgical intervention. By reviewing the current understanding of STODS etiologies, we will attempt to outline a rationale for a tailored GOLD optimization depending on the ocular surgical insult. With a bench-to-bedside approach, we will highlight clinical examples of effective GOLD perioperative optimization that can mitigate STODS' deleterious effect on preoperative imaging and postoperative healing.