Establishment of Immortalized Human Amniotic Mesenchymal Stem Cells

Transplanted artificial amnion membrane enhanced wound healing in third-degree burn injury diabetic mouse model

Introduction

Wound healing is severely compromised in patients with diabetes owing to factors such poor blood circulation, delayed immune response, elevated blood sugar levels, and neuropathy. Although the development of new wound healing products and prevention of serious complications such as infections in wounds have received substantial interest, wound healing remains a challenge in regenerative medicine. Burn wounds, especially third-degree burns, are difficult to treat because they are associated with immune and inflammatory reactions and distributive shock. Wound care and treatment that protects the burn site from infection and allows wound healing can be achieved with bioengineered wound dressings. However, few studies have reported effective dressings for third-degree burn wounds, making it important to develop new dressing materials.

Methods

In this study, we developed an artificial amniotic membrane (AM) using epithelial and mesenchymal cells derived from human amnion as a novel dressing material. The artificial AM was applied to the wound of a diabetic third-degree burn model and its wound healing ability was evaluated.

Results

This artificial amnion produced multiple growth factors associated with angiogenesis, fibroblast proliferation, and anti-inflammation. In addition, angiogenesis and granulation tissue formation were promoted in the artificial AM-treated mouse group compared with the control group. Furthermore, the inflammatory phase was prolonged in the control group.

Conclusions

Our preliminary results indicate that the artificial AM might be useful as a new dressing for refractory ulcers and third-degree burns. This artificial AM-based material represents great potential for downstream clinical research and treatment of diabetes patients with third-degree burns.

Stem-Cell-Driven Chondrogenesis: Perspectives on Amnion-Derived Cells

Regenerative medicine harnesses stem cells' capacity to restore damaged tissues and organs. In vitro methods employing specific bioactive molecules, such as growth factors, bio-inductive scaffolds, 3D cultures, co-cultures, and mechanical stimuli, steer stem cells toward the desired differentiation pathways, mimicking their natural development. Chondrogenesis presents a challenge for regenerative medicine. This intricate process involves precise modulation of chondro-related transcription factors and pathways, critical for generating cartilage. Cartilage damage disrupts this process, impeding proper tissue healing due to its unique mechanical and anatomical characteristics. Consequently, the resultant tissue often forms fibrocartilage, which lacks adequate mechanical properties, posing a significant hurdle for effective regeneration. This review comprehensively explores studies showcasing the potential of amniotic mesenchymal stem cells (AMSCs) and amniotic epithelial cells (AECs) in chondrogenic differentiation. These cells exhibit innate characteristics that position them as promising candidates for regenerative medicine. Their capacity to differentiate toward chondrocytes offers a pathway for developing effective regenerative protocols. Understanding and leveraging the innate properties of AMSCs and AECs hold promise in addressing the challenges associated with cartilage repair, potentially offering superior outcomes in tissue regeneration.

Strategies for immortalisation of amnion-derived mesenchymal and epithelial cells

Mesenchymal (human amniotic mesenchymal stem cell [HAMSC]) and epithelial cells (human amnion epithelial cell [HAEC]) derived from human amniotic membranes possess characteristics of pluripotency. However, the pluripotency of HAMSC and HAEC are sustained only for a finite period. This in vitro cell growth can be extended by cell immortalisation. Many well-defined immortalisation systems have been used for artificially overexpressing genes such as human telomerase reverse transcriptase in HAMSC and HAEC leading to controlled and prolonged cell proliferation. In recent years, much progress has been made in our understanding of the cellular machinery that regulates the cell cycle when immortalised. This review summarises the current understanding of molecular mechanisms that contribute to cell immortalisation, the strategies that have been employed to immortalise amnion-derived cell types, and their likely applications in regenerative medicine.

Establishment and characterization of cell lines from human endometrial epithelial and mesenchymal cells from patients with endometriosis

OBJECTIVE

To establish and characterize cell lines derived from human endometrial epithelial cells (ECs) and mesenchymal cells (MCs) from patients with and without endometriosis.

DESIGN

In vitro experimental study.

SETTING

University and national cancer center research institute.

PATIENT(S)

Two women with endometriosis and two women without endometriosis.

INTERVENTION(S)

Sampling of endometrial ECs and MCs.

MAIN OUTCOME MEASURE(S)

Establishing immortalized endometrial ECs and MCs with quantitative reverse transcription-polymerase chain reaction (qRT-PCR), immunocytochemical analysis, and RNA sequence profiling performed to characterize the immortalized cells and a cell proliferation assay, three-dimensional culture, and assays for hormone responses performed to characterize the features of ECs.

RESULT(S)

The qRT-PCR, immunocytochemical analysis, and Western blot analysis revealed that the ECs and MCs maintained their original features. Moreover, the immortalized cells were found to retain responsiveness to sex steroid hormones. The ECs formed a gland-like structure in three-dimensional culture, indicating the maintenance of normal EC phenotypes. The RNA sequence profiling, principal component analysis, and clustering analysis showed that the gene expression patterns of the immortalized cells were different from those of cancer cells. Several signaling pathways that were statistically significantly enriched in ECs and MCs with endometriosis were revealed.

CONCLUSION(S)

We successfully obtained four paired immortalized endometrial ECs and MCs from patients with and without endometriosis. Using these cells could help identify diagnostic and therapeutic targets for endometriosis. The cell lines established in this study will thus serve as powerful experimental tools in the study of endometriosis.

Myogenic differentiation of human amniotic mesenchymal cells and its tissue repair capacity on volumetric muscle loss

Stem cell-based tissue engineering therapy is the most promising method for treating volumetric muscle loss. Human amniotic mesenchymal cells possess characteristics similar to those of embryonic stem cells. In this study, we verified the stem cell characteristics of human amniotic mesenchymal cells by the flow cytometry analysis, and osteogenic and adipogenic differentiation. Through induction with the DNA demethylating agent 5-azacytidine, human amniotic mesenchymal cells can undergo myogenic differentiation and express skeletal muscle cell-specific markers such as desmin and MyoD. The Wnt/β-catenin signaling pathway also plays an important role. After 5-azacytidine-induced human amniotic mesenchymal cells were implanted into rat tibialis anterior muscle with volumetric muscle loss, we observed increased angiogenesis and improved local tissue repair. We believe that human amniotic mesenchymal cells can serve as a potential source of cells for skeletal muscle tissue engineering.

Differential response of immortalized human amnion mesenchymal and epithelial cells against oxidative stress

Cells are equipped with various antioxidant defense factors to antagonize insults from reactive oxygen species (ROS), thus the antioxidant capacity has been characterized by a variety of cellular responses during the pathophysiological processes. Amniotic cells have been extensively applied in clinical practice for burn treatment, corneal repair, and tissue regeneration. However, the antioxidative properties of amniotic cells have not yet been fully understood. Therefore, the current study was aimed to observe the response of amniotic cells against ROS stimuli, and to investigate the underlying molecular mechanisms. The immortalized human amniotic mesenchymal cells (iHAMs) and immortalized human amniotic epithelial cells (iHAEs) were used. The human skin fibroblast (HSF) was used as a control cell line. Changes in intracellular ROS generation, cell viability, and cellular morphology were investigated to reveal the response of amniotic cells against oxidative stresses induced by x-rays and hydrogen peroxide. In addition, expression of apoptosis-related proteins and response to antioxidative stress was also examined. The intracellular ROS level and cell apoptosis in iHAMs was remarkably increased. iHAEs showed relatively high resistance to ROS stimulation, which can be attributed to the high SOD2 expression and up-regulation of Nrf2, HO-1 after x-rays exposure. In contrast, iHAMs were found sensitive to oxidative damage. Expression of caspase-3, caspase-8 and BAX was increased, whereas down-regulation of Bcl-xL, Nrf2, HO-1, and TrxR-1. Taken together, findings have highlighted the characterization of response of amniotic derived epithelial and mesenchymal cells to oxidative stress. In physiological processes, iHAMs may play an important role to maintain the homeostasis of the pregnancy environment. However, under oxidative stimulations, iHAEs provides protection against oxidative damage in amnion tissue.

A Human Amnion-Derived Extracellular Matrix-Coated Cell-Free Scaffold for Cartilage Repair: In Vitro and In Vivo Studies

OBJECTIVE

Extracellular matrix (ECM) derived from human amniotic mesenchymal cells (HAMs) has various biological activities. In this study, we developed a novel HAM-derived ECM-coated polylactic-co-glycolic acid (ECM-PLGA) scaffold, examined its property on mesenchymal cells, and investigated its potential as a cell-free scaffold for cartilage repair.

MATERIALS AND METHODS

ECM-PLGA scaffolds were developed by inoculating HAM on a PLGA. After decellularization by irradiation, accumulated ECM was examined. Exogenous cell growth and differentiation of rat mesenchymal stem cells (MSCs) on the ECM-PLGA were analyzed in vitro by cell attachment/proliferation assay and reverse transcription-polymerase chain reaction. The cell-free ECM-PLGA scaffolds were implanted into osteochondral defects in the trochlear groove of rat knees. After 4, 12, or 24 weeks, the animals were sacrificed and the harvested tissues were examined histologically.

RESULTS

The ECM-PLGA contained ECM that mimicked natural amniotic stroma that contains type I collagen, fibronectin, hyaluronic acid, and chondroitin sulfates. The ECM-PLGA showed excellent properties of cell attachment and proliferation. MSCs inoculated on the ECM-PLGA scaffold showed accelerated type II collagen mRNA expression after 3 weeks in culture. The ECM-PLGA implanted into an osteochondral defect in rat knees induced gradual tissue regeneration and resulted in hyaline cartilage repair, which was better than that in the empty control group.

CONCLUSION

These in vitro and in vivo experiments show that the cell-free scaffold composed of HAM-derived ECM and PLGA provides a favorable growth environment for MSCs and facilitates the cartilage repair process. The ECM-PLGA may become a "ready-made" biomaterial for cartilage repair therapy.

Amnion-Epithelial-Cell-Derived Exosomes Demonstrate Physiologic State of Cell under Oxidative Stress

At term, the signals of fetal maturity and feto-placental tissue aging prompt uterine readiness for delivery by transitioning quiescent myometrium to an active stage. It is still unclear how the signals reach the distant myometrium. Exosomes are a specific type of extracellular vesicle (EVs) that transport molecular signals between cells, and are released from a wide range of cells, including the maternal and fetal cells. In this study, we hypothesize that i) exosomes act as carriers of signals in utero-placental compartments and ii) exosomes reflect the physiologic status of the origin cells. The primary aims of this study were to determine exosomal contents in exosomes derived from primary amnion epithelial cells (AEC). We also determined the effect of oxidative stress on AEC derived exosomal cargo contents. AEC were isolated from amniotic membrane obtained from normal, term, not in labor placentae at delivery, and culture under standard conditions. Oxidative stress was induced using cigarette smoke extract for 48 hours. AEC-conditioned media were collected and exosomes isolated by differential centrifugations. Both growth conditions (normal and oxidative stress induced) produced cup shaped exosomes of around 50 nm, expressed exosomes enriched markers, such as CD9, CD63, CD81 and HSC70, embryonic stem cell marker Nanog, and contained similar amounts of cell free AEC DNA. Using confocal microscopy, the colocalization of histone (H) 3, heat shock protein (HSP) 70 and activated form of pro-senescence and term parturition associated marker p38 mitogen activated protein kinase (MAPK) (P-p38 MAPK) co-localized with exosome enrich marker CD9. HSP70 and P-p38 MAPK were significantly higher in exosomes from AEC grown under oxidative stress conditions than standard conditions (p<0.05). Finally, mass spectrometry and bioinformatics analysis identified 221 different proteins involved in immunomodulatory response and cell-to-cell communication. This study determined AEC exosome characteristics and their cargo reflected the physiologic status of the cell of origin and suggests that AEC-derived exosomal p38 MAPK plays a major role in determining the fate of pregnancy. Understanding the propagation of fetal signals and their mechanisms in normal term pregnancies can provide insights into pathologic activation of such signals associated with spontaneous preterm parturitions.

Stem cells: a promising source for vascular regenerative medicine

The rising and diversity of many human vascular diseases pose urgent needs for the development of novel therapeutics. Stem cell therapy represents a challenge in the medicine of the twenty-first century, an area where tissue engineering and regenerative medicine gather to provide promising treatments for a wide variety of diseases. Indeed, with their extensive regeneration potential and functional multilineage differentiation capacity, stem cells are now highlighted as promising cell sources for regenerative medicine. Their multilineage differentiation involves environmental factors such as biochemical, extracellular matrix coating, oxygen tension, and mechanical forces. In this review, we will focus on human stem cell sources and their applications in vascular regeneration. We will also discuss the different strategies used for their differentiation into both mature and functional smooth muscle and endothelial cells.

Human Amnion-Derived Stem Cells Have Immunosuppressive Properties on NK Cells and Monocytes

Human amnion-derived cells are considered to be a promising alternative cell source for their potential clinical use in tissue engineering and regenerative medicine because of their proliferation and differentiation ability. The cells can easily be obtained from human amnion, offering a potential source without medical intervention. It has been proven that human amnion-derived cells express immunosuppressive factors CD59 and HLA-G, implying that they may have an immunosuppressive function. To assess the immunosuppressive activity, we investigated the effect of human amnion-derived cells on NK cell and monocyte function. Amnion-derived cells inhibited the cytotoxicity of NK cells to K562 cells. The inhibition depended on the NK/amnion-derived cell ratio. The inhibition of NK cytotoxicity was recovered by continuous culturing without amnion-derived cells. The inhibition of NK cytotoxicity was related to the downregulation of the expression of the activated NK receptors and the production of IFN-γ, as well as the upregulation of the expression of IL-10 and PGE2 in human amnion-derived cells. The addition of antibody to IL-10 or PGE2 inhibitor tended to increase NK cytotoxicity. IL-10 and PGE2 might be involved in the immunosuppressive activity of amniotic cells toward NK cells. Amniotic cells also suppressed the activity of cytokine production in monocytes analyzed with TNF-α and IL-6. These data suggested that amniotic cells have immunosuppressive activity.