Differentiation of Human Amniotic Mesenchymal Stem Cells into Human Anterior Cruciate Ligament Fibroblast Cells by In Vitro Coculture

[Research on Runx2 gene induced differentiation of human amniotic mesenchymal stem cells into ligament fibroblasts in vitro and promotion of tendon-bone healing in rabbits]

Objective

To investigate whether the Runx2 gene can induce the differentiation of human amniotic mesenchymal stem cells (hAMSCs) to ligament fibroblasts in vitro and promote the tendon-bone healing in rabbits.

Methods

hAMSCs were isolated from the placentas voluntarily donated from healthy parturients and passaged, and then identified by flow cytometric identification. Adenoviral vectors carrying Runx2 gene (Ad-Runx2) and empty vector adenovirus (Ad-NC) were constructed and viral titer assay; then, the 3rd generation hAMSCs were transfected with Ad-Runx2 (Ad-Runx2 group) or Ad-NC (Ad-NC group). The real-time fluorescence quantitative PCR and Western blot were used to detect Runx2 gene and protein expression to verify the effectiveness of Ad-Runx2 transfection of hAMSCs; and at 3 and 7 days after transfection, real-time fluorescence quantitative PCR was further used to detect the expressions of ligament fibroblast-related genes [vascular endothelial growth factor (VEGF), collagen type Ⅰ, Fibronectin, and Tenascin-C]. The hAMSCs were used as a blank control group. The hAMSCs, hAMSCs transfected with Ad-NC, and hAMSCs were mixed with Matrigel according to the ratio of 1 : 1 and 1 : 2 to construct the cell-scaffold compound. Cell proliferation was detected by cell counting kit 8 (CCK-8) assay, and the corresponding cell-scaffold compound with better proliferation were taken for subsequent animal experiments. Twelve New Zealand white rabbits were randomly divided into 4 groups of sham operation group (Sham group), anterior cruciate ligament reconstruction group (ACLR group), anterior cruciate ligament reconstruction+hAMSCs transfected with Ad-NC-scaffold compound group (Ad-NC group), and anterior cruciate ligament reconstruction+hAMSCs transfected with Ad-Runx2-scaffold compound group (Ad-Runx2 group), with 3 rabbits in each group. After preparing the ACL reconstruction model, the Ad-NC group and the Ad-Runx2 group injected the optimal hAMSCs-Matrigel compunds into the bone channel correspondingly. The samples were taken for gross, histological (HE staining and sirius red staining), and immunofluorescence staining observation at 1 month after operation to evaluate the inflammatory cell infiltration as well as collagen and Tenascin-C content in the ligament tissues.

Results

Flow cytometric identification of the isolated cells conformed to the phenotypic characteristics of MSCs. The Runx2 gene was successfully transfected into hAMSCs. Compared with the Ad-NC group, the relative expressions of VEGF and collagen type Ⅰ genes in the Ad-Runx2 group significantly increased at 3 and 7 days after transfection ( P<0.05), Fibronectin significantly increased at 3 days ( P<0.05), and Tenascin-C significantly increased at 3 days and decreased at 7 days ( P<0.05). CCK-8 detection showed that there was no significant difference ( P>0.05) in the cell proliferation between groups and between different time points after mixed culture of two ratios. So the cell-scaffold compound constructed in the ratio of 1∶1 was selected for subsequent experiments. Animal experiments showed that at 1 month after operation, the continuity of the grafted tendon was complete in all groups; HE staining showed that the tissue repair in the Ad-Runx2 group was better and there were fewer inflammatory cells when compared with the ACLR group and the Ad-NC group; sirius red staining and immunofluorescence staining showed that the Ad-Runx2 group had more collagen typeⅠ and Ⅲ fibers, tending to form a normal ACL structure. However, the fluorescence intensity of Tenascin-C protein was weakening when compared to the ACLR and Ad-NC groups.

Conclusion

Runx2 gene transfection of hAMSCs induces directed differentiation to ligament fibroblasts and promotes tendon-bone healing in reconstructed anterior cruciate ligament in rabbits.

Human acellular amniotic membrane scaffolds encapsulating juvenile cartilage fragments accelerate the repair of rabbit osteochondral defects

Aims

The purpose of this study was to explore a simple and effective method of preparing human acellular amniotic membrane (HAAM) scaffolds, and explore the effect of HAAM scaffolds with juvenile cartilage fragments (JCFs) on osteochondral defects.

Methods

HAAM scaffolds were constructed via trypsinization from fresh human amniotic membrane (HAM). The characteristics of the HAAM scaffolds were evaluated by haematoxylin and eosin (H&E) staining, picrosirius red staining, type II collagen immunostaining, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Human amniotic mesenchymal stem cells (hAMSCs) were isolated, and stemness was verified by multilineage differentiation. Then, third-generation (P3) hAMSCs were seeded on the HAAM scaffolds, and phalloidin staining and SEM were used to detect the growth of hAMSCs on the HAAM scaffolds. Osteochondral defects (diameter: 3.5 mm; depth: 3 mm) were created in the right patellar grooves of 20 New Zealand White rabbits. The rabbits were randomly divided into four groups: the control group (n = 5), the HAAM scaffolds group (n = 5), the JCFs group (n = 5), and the HAAM + JCFs group (n = 5). Macroscopic and histological assessments of the regenerated tissue were evaluated to validate the treatment results at 12 weeks.

Results

In vitro, the HAAM scaffolds had a network structure and possessed abundant collagen. The HAAM scaffolds had good cytocompatibility, and hAMSCs grew well on the HAAM scaffolds. In vivo, the macroscopic scores of the HAAM + JCFs group were significantly higher than those of the other groups. In addition, histological assessments demonstrated that large amounts of hyaline-like cartilage formed in the osteochondral defects in the HAAM + JCFs group. Integration with surrounding normal cartilage and regeneration of subchondral bone in the HAAM + JCFs group were better than those in the other groups.

Conclusion

HAAM scaffolds combined with JCFs promote the regenerative repair of osteochondral defects.

Cite this article: Bone Joint Res 2022;11(6):349–361.

hAMSC Sheet Promotes Repair of Rabbit Osteochondral Defects

Osteochondral lesion is clinically common disease, which has been recognized as one of the contributing factors of significant morbidity. Although current treatments have achieved good outcomes, some undesirable complications and failures are not uncommon. Cell sheet technology (CST), an innovative technology to harvest seed cells and preserve abundant ECM, has been widely used in various tissue regeneration. For osteochondral lesion, many studies focus on using CST to repair osteochondral lesion and have achieved good outcomes. In the previous study, we have demonstrated that hAMSC sheet had a positive effect on osteochondral lesion. Therefore, this study is aimed at comparing the effect of noninduced hAMSC sheet with chondrogenically induced hAMSC sheet on osteochondral lesion and cartilage regeneration.

Stem/progenitor cells in fetuses and newborns: overview of immunohistochemical markers

Microanatomy of the vast majority of human organs at birth is characterized by marked differences as compared to adult organs, regarding their architecture and the cell types detectable at histology. In preterm neonates, these differences are even more evident, due to the lower level of organ maturation and to ongoing cell differentiation. One of the most remarkable finding in preterm tissues is the presence of huge amounts of stem/progenitor cells in multiple organs, including kidney, brain, heart, adrenals, and lungs. In other organs, such as liver, the completely different burden of cell types in preterm infants is mainly related to the different function of the liver during gestation, mainly focused on hematopoiesis, a function that is taken by bone marrow after birth. Our preliminary studies showed that the antigens expressed by stem/progenitors differ significantly from one organ to the next. Moreover, within each developing human tissue, reactivity for different stem cell markers also changes during gestation, according with the multiple differentiation steps encountered by each progenitor during development. A better knowledge of stem/progenitor cells of preterms will allow neonatologists to boost preterm organ maturation, favoring the differentiation of the multiple cells types that characterize each organ in at term neonates.

Human mesenchymal stem cell treatment of premature ovarian failure: new challenges and opportunities

Premature ovarian failure (POF) is one of the common disorders found in women leading to 1% female infertility. Clinical features of POF are hypoestrogenism or estrogen deficiency, increased gonadotropin level, and, most importantly, amenorrhea. With the development of regenerative medicine, human mesenchymal stem cell (hMSC) therapy brings new prospects for POF. This study aimed to describe the types of MSCs currently available for POF therapy, their biological characteristics, and their mechanism of action. It reviewed the latest findings on POF to provide the theoretical basis for further investigation and clinical therapy.

In Vitro Innovation of Tendon Tissue Engineering Strategies

Tendinopathy is the term used to refer to tendon disorders. Spontaneous adult tendon healing results in scar tissue formation and fibrosis with suboptimal biomechanical properties, often resulting in poor and painful mobility. The biomechanical properties of the tissue are negatively affected. Adult tendons have a limited natural healing capacity, and often respond poorly to current treatments that frequently are focused on exercise, drug delivery, and surgical procedures. Therefore, it is of great importance to identify key molecular and cellular processes involved in the progression of tendinopathies to develop effective therapeutic strategies and drive the tissue toward regeneration. To treat tendon diseases and support tendon regeneration, cell-based therapy as well as tissue engineering approaches are considered options, though none can yet be considered conclusive in their reproduction of a safe and successful long-term solution for full microarchitecture and biomechanical tissue recovery. In vitro differentiation techniques are not yet fully validated. This review aims to compare different available tendon in vitro differentiation strategies to clarify the state of art regarding the differentiation process.

Enhanced tenogenic differentiation and tendon-like tissue formation by Scleraxis overexpression in human amniotic mesenchymal stem cells

Tendon and ligament injuries are not uncommon in clinics and have poor self-healing capacity due to their bloodless and slow-proliferative nature. Promoting the repair or reconstruction of an injured structure is an urgent problem. While Scleraxis (Scx) is a highly specific tendon cell marker, its function has not been explored to a large extent. Hence, Recombinant adenovirus was used to study the influence of Scx overexpression on directional differentiation of human amniotic mesenchymal stem cells (hMSCAs). hAMSCs modified with Scx could dramatically enhance the gene expression of tendon-related molecules, containing Scx, collagens I and III, Tenascin-C, fibronectin, matrix metalloproteinase-2 (MMP-2), lysyl oxidase-1 (LOX-1) and Tenomodulin at all-time points (P < 0.05), and the secretion of collagen I and III, fibronectin and Tenascin-C over time (P < 0.05) but did not impact the cell proliferation capacity (P > 0.05). Immunofluorescence staining showed the cobweb-like fusion of collagen I and fibronectin in the AdScx group on day 7, with higher average fluorescence intensity than the control (P < 0.05). After mixing with Matrigel, transplants were subcutaneously implanted in nude mice, obvious inflammation and rejection of immune response were not observed and HE staining showed a histological feature of swirl of fibers is closely linked in parallel in hAMSCs modified with Scx. On the contrary, in the control group, an unorganized connective structure with cell distributed randomly was spotted. The results of promoted directional differentiation of stem cells and the spatial structure of the normal tendon tissue in three-dimensional space manifested that Scx can be used as a specific marker for tendon cells, and as a positive regulator for directional differentiation of hAMSCs, which is possible to be applied to novel therapeutics for clinical tendon and ligament injury by hAMSCs modified with Scx.

Fibroblast growth factor 2-induced human amniotic mesenchymal stem cells combined with autologous platelet rich plasma augmented tendon-to-bone healing

Objective

The purpose of this study was to explore the effect of fibroblast growth factor 2 (FGF-2) on collagenous fibre formation and the osteogenic differentiation of human amniotic mesenchymal stem cells (hAMSCs) in vitro, as well as the effect of FGF-2–induced hAMSCs combined with autologous platelet-rich plasma (PRP) on tendon-to-bone healing in vivo.

Methods

In vitro, hAMSCs were induced by various concentrations of FGF-2 (0, 10, 20, and 40 ​ng/ml) for 14 days, and the outcomes of ligamentous differentiation and osteogenic differentiation were detected by quantitative real-time reverse transcription PCR, Western blot, immunofluorescence, and picrosirius red staining. In addition, a lentivirus carrying the FGF-2 gene was used to transfect hAMSCs, and transfection efficiency was detected by quantitative real time reverse transcription PCR (qRT-PCR) and Western blot. In vivo, the effect of hAMSCs transfected with the FGF-2 gene combined with autologous PRP on tendon-to-bone healing was detected via histological examination, as well as biomechanical analysis and radiographic analysis.

Results

In vitro, different concentrations of FGF-2 (10, 20, and 40 ​ng/ml) all promoted the ligamentous differentiation and osteogenic differentiation of hAMSCs, and the low concentration of FGF-2 (10 ​ng/ml) had a good effect on differentiation. In addition, the lentivirus carrying the FGF-2 gene was successfully transfected into hAMSCs with an optimal multiplicity of infection (MOI) (50), and autologous PRP was prepared successfully. In vivo, the hAMSCs transfected with the FGF-2 gene combined with autologous PRP had a better effect on tendon-to-bone healing than the other groups (p ​< ​0.05), as evidenced by histological examination, biomechanical analysis, and radiographic analysis.

Conclusion

hAMSCs transfected with the FGF-2 gene combined with autologous PRP could augment tendon-to-bone healing in a rabbit extra-articular model.

The translational potential of this article

hAMSCs transfected with the FGF-2 gene combined with autologous PRP may be a good clinical treatment for tendon-to-bone healing, especially for acute sports-related tendon–ligament injuries.

Schnurri-3 regulates BMP9-induced osteogenic differentiation and angiogenesis of human amniotic mesenchymal stem cells through Runx2 and VEGF

Human amniotic mesenchymal stem cells (hAMSCs) are multiple potent progenitor cells (MPCs) that can differentiate into different lineages (osteogenic, chondrogenic, and adipogenic cells) and have a favorable capacity for angiogenesis. Schnurri-3 (Shn3) is a large zinc finger protein related to Drosophila Shn, which is a critical mediator of postnatal bone formation. Bone morphogenetic protein 9 (BMP9), one of the most potent osteogenic BMPs, can strongly upregulate various osteogenesis- and angiogenesis-related factors in MSCs. It remains unclear how Shn3 is involved in BMP9-induced osteogenic differentiation coupled with angiogenesis in hAMSCs. In this investigation, we conducted a comprehensive study to identify the effect of Shn3 on BMP9-induced osteogenic differentiation and angiogenesis in hAMSCs and analyze the responsible signaling pathway. The results from in vitro and in vivo experimentation show that Shn3 notably inhibits BMP9-induced early and late osteogenic differentiation of hAMSCs, expression of osteogenesis-related factors, and subcutaneous ectopic bone formation from hAMSCs in nude mice. Shn3 also inhibited BMP9-induced angiogenic differentiation, expression of angiogenesis-related factors, and subcutaneous vascular invasion in mice. Mechanistically, we found that Shn3 prominently inhibited the expression of BMP9 and activation of the BMP/Smad and BMP/MAPK signaling pathways. In addition, we further found activity on runt-related transcription factor 2 (Runx2), vascular endothelial growth factor (VEGF), and the target genes shared by BMP and Shn3 signaling pathways. Silencing Shn3 could dramatically enhance the expression of Runx2, which directly regulates the downstream target VEGF to couple osteogenic differentiation with angiogenesis. To summarize, our findings suggested that Shn3 significantly inhibited the BMP9-induced osteogenic differentiation and angiogenesis in hAMSCs. The effect of Shn3 was primarily seen through inhibition of the BMP/Smad signaling pathway and depressed expression of Runx2, which directly regulates VEGF, which couples BMP9-induced osteogenic differentiation with angiogenesis.

FGF-2-Induced Human Amniotic Mesenchymal Stem Cells Seeded on a Human Acellular Amniotic Membrane Scaffold Accelerated Tendon-to-Bone Healing in a Rabbit Extra-Articular Model

Background

FGF-2 (basic fibroblast growth factor) has a positive effect on the proliferation and differentiation of many kinds of MSCs. Therefore, it represents an ideal molecule to facilitate tendon-to-bone healing. Nonetheless, no studies have investigated the application of FGF-2-induced human amniotic mesenchymal stem cells (hAMSCs) to accelerate tendon-to-bone healing in vivo.

Objective

The purpose of this study was to explore the effect of FGF-2 on chondrogenic differentiation of hAMSCs in vitro and the effect of FGF-2-induced hAMSCs combined with a human acellular amniotic membrane (HAAM) scaffold on tendon-to-bone healing in vivo.

Methods

In vitro, hAMSCs were transfected with a lentivirus carrying the FGF-2 gene, and the potential for chondrogenic differentiation of hAMSCs induced by the FGF-2 gene was assessed using immunofluorescence and toluidine blue (TB) staining. HAAM scaffold was prepared, and hematoxylin and eosin (HE) staining and scanning electron microscopy (SEM) were used to observe the microstructure of the HAAM scaffold. hAMSCs transfected with and without FGF-2 were seeded on the HAAM scaffold at a density of 3 × 10⁵ cells/well. Immunofluorescence staining of vimentin and phalloidin staining were used to confirm cell adherence and growth on the HAAM scaffold. In vivo, the rabbit extra-articular tendon-to-bone healing model was created using the right hind limb of 40 New Zealand White rabbits. Grafts mimicking tendon-to-bone interface (TBI) injury were created and subjected to treatment with the HAAM scaffold loaded with FGF-2-induced hAMSCs, HAAM scaffold loaded with hAMSCs only, HAAM scaffold, and no special treatment. Macroscopic observation, imageological analysis, histological assessment, and biomechanical analysis were conducted to evaluate tendon-to-bone healing after 3 months.

Results

In vitro, cartilage-specific marker staining was positive for the FGF-2 overexpression group. The HAAM scaffold displayed a netted structure and mass extracellular matrix structure. hAMSCs or hAMSCs transfected with FGF-2 survived on the HAAM scaffold and grew well. In vivo, the group treated with HAAM scaffold loaded with FGF-2-induced hAMSCs had the narrowest bone tunnel after three months as compared with other groups. In addition, macroscopic and histological scores were higher for this group than for the other groups, along with the best mechanical strength.

Conclusion

hAMSCs transfected with FGF-2 combined with the HAAM scaffold could accelerate tendon-to-bone healing in a rabbit extra-articular model.

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.

Human amniotic mesenchymal stem cells improve the follicular microenvironment to recover ovarian function in premature ovarian failure mice

BACKGROUND

Many adult women younger than 40 years old have premature ovarian failure (POF) and infertility. Previous studies confirmed that different tissue-derived stem cells could restore ovarian function and folliculogenesis in chemotherapy-induced POF mice. The aim of this study was to explore the therapeutic efficacy and underlying mechanisms of human amniotic mesenchymal stem cells (hAMSCs) transplantation for hydrogen peroxide-induced ovarian damage.

METHODS

Bilateral ovaries of female mice were burned with 10% hydrogen peroxide to establish a POF model. After 24 h of treatment, hAMSCs and diethylstilbestrol were administered to POF mice by intraperitoneal injection and intragastric administration, respectively. After either 7 or 14 days, ovarian function was evaluated by the oestrus cycle, hormone levels, ovarian index, fertility rate, and ovarian morphology. The karyotype was identified in offspring by the G-banding technique. hAMSCs tracking, immunohistochemical staining, and real-time polymerase chain reaction (PCR) were used to assess the molecular mechanisms of injury and repair.

RESULTS

The oestrus cycle was recovered after hAMSCs transplantation at 7 and 14 days. Oestrogen levels increased, while follicle-stimulating hormone levels decreased. The ovarian index, fertility rate, and population of follicles at different stages were significantly increased. The newborn mice had no obvious deformity and showed normal growth and development. The normal offspring mice were also fertile. The tracking of hAMSCs revealed that they colonized in the ovarian stroma. Immunohistochemical and PCR analyses indicated that changes in proteins and genes might affect mature follicle formation.

CONCLUSIONS

These results suggested that hAMSCs transplantation can improve injured ovarian tissue structure and function in oxidatively damaged POF mice. Furthermore, the mechanisms of hAMSCs are related to promoting follicular development, granulosa cell proliferation, and secretion function by improving the local microenvironment of the ovary.

Effect of Optimized Concentrations of Basic Fibroblast Growth Factor and Epidermal Growth Factor on Proliferation of Fibroblasts and Expression of Collagen: Related to Pelvic Floor Tissue Regeneration

Background:

Fibroblasts were the main seed cells in the studies of tissue engineering of the pelvic floor ligament. Basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) were widely studied but at various concentrations. This study aimed to optimize the concentrations of combined bFGF and EGF by evaluating their effects on proliferation and collagen secretion of fibroblasts.

Methods:

Fibroblasts were differentiated from rat adipose mesenchymal stem cells (ADSCs). Flow cytometry and immunohistochemistry were used for cell identification. The growth factors were applied at concentrations of 0, 1, 10, and 100 ng/ml as three groups: (1) bFGF alone, (2) EGF alone, and (3) bFGF mixed with EGF. Cell proliferation was evaluated by Cell Counting Kit-8 assays. Expression of Type I and III collagen (Col-I and Col-III) mRNAs was evaluated by real-time quantitative reverse transcription-polymerase chain reaction. Statistical analysis was performed with SPSS software and GraphPad Prism using one-way analysis of variance and multiple t-test.

Results:

ADSCs were successfully isolated from rat adipose tissue as identified by expression of typical surface markers CD29, CD44, CD90, and CD45 in flow cytometry. Fibroblasts induced from ADSC, compared with ADSCs, were with higher mRNA expression levels of Col I and Col III (F = 1.29, P = 0.0390). bFGF, EGF, and the mixture of bFGF with EGF can enhanced fibroblasts proliferation, and the concentration of 10 ng/ml of the mixture of bFGF with EGF displayed most effectively (all P < 0.05). The expression levels of Col-I and Col-III mRNAs in fibroblasts displayed significant increases in the 10 ng/ml bFGF combined with EGF group (all P < 0.05).

Conclusions:

The optimal concentration of both bFGF and EGF to promote cell proliferation and collagen expression in fibroblasts was 10 ng/ml at which fibroblasts grew faster and secreted more Type I and III collagens into the extracellular matrix, which might contribute to the stability of the pelvic floor microenvironment.