Importance of Stem Cell Migration and Angiogenesis Study for Regenerative Cell-based Therapy: A Review

G-CSF-mobilized peripheral blood mononuclear cells combined with platelet-rich plasma restored the ovarian function of aged rats

BACKGROUND

Regenerative medicine with peripheral blood mononuclear cell (PBMC) transplantation sheds light on the issue of premature ovarian insufficiency (POI). However, the efficiency of PBMC treatment in natural ovarian aging (NOA) remains unclear.

METHODS

Thirteen-month-old female Sprague-Dawley (SD) rats were used to verify the NOA model. Seventy-two NOA rats were randomly divided into three groups: the NOA control group, PBMC group, and PBMC+platelet-rich plasma (PRP) group. PBMCs and PRP were transplanted by intraovarian injection. The effects on ovarian function and fertility were measured after transplantation.

RESULTS

Transplantation of PBMCs could restore the normal estrous cycle, consistent with the recovery of serum sex hormone levels, increased follicle numbers at all stages, and restoration of fertility by facilitating pregnancy and live birth. Moreover, when combined with PRP injection, these effects were more significant. The male-specific SRY gene was detected in the ovary at all four time points, suggesting that PBMCs continuously survived and functioned in NOA rats. In addition, after PBMC treatment, the expression of angiogenesis-related and glycolysis-related markers in the ovaries was upregulated, which indicated that these effects were associated with angiogenesis and glycolysis.

CONCLUSIONS

PBMC transplantation restores the ovarian functions and fertility of NOA rats, and PRP could enhance the efficiency. Increased ovarian vascularization, follicle production, and glycolysis are likely the major mechanisms.

Core-shell oxygen-releasing fibers for annulus fibrosus repair in the intervertebral disc of rats

The repair of annulus fibrosus (AF) defect after discectomy in the intervertebral disc (IVD) has presented a challenge over the past decade. Hostile microenvironments in the IVD, including, compression and hypoxia, are critical issues that require special attention. Till date, little information is available on potential strategies to cope with the hypoxia dilemma in AF defect sites. In this study, perfluorotributylamine (PFTBA) core-shell fibers were fabricated by coaxial electrospinning to construct oxygen-releasing scaffold for promoting endogenous repair in the AF after discectomy. We demonstrated that PFTBA fibers (10% chitosan, chitosan: PCL, 1:6) could release oxygen for up to 144 ​h. The oxygen released from PFTBA fibers was found to protect annulus fibrosus stem cells (AFSCs) from hypoxia-induced apoptosis. In addition, the PFTBA fibers were able to promote proliferation, migration and extracellular matrix (ECM) production in AFSCs under hypoxia, highlighting their therapeutic potential in AF defect repair. Subsequent in vivo studies demonstrated that oxygen-supplying fibers were capable of ameliorating disc degeneration after discectomy, which was evidenced by improved disc height and morphological integrity in rats with the oxygen-releasing scaffolds. Further transcriptome analysis indicated that differential expression genes (DEGs) were enriched in "oxygen transport" and "angiogenesis", which likely contributed to their beneficial effect on endogenous AF regeneration. In summary, the oxygen-releasing scaffold provides novel insights into the oxygen regulation by bioactive materials and raises the therapeutic possibility of oxygen supply strategies for defect repair in AF, as well as other aerobic tissues.

The Potential Application of Human Gingival Fibroblast-Conditioned Media in Pulp Regeneration: An In Vitro Study

Regenerative endodontic treatment based on tissue engineering has recently gained interest in contemporary restorative dentistry. However, low survival rates and poor potential differentiation of stem cells could undermine the success rate of pulp regenerative therapy. Human gingival fibroblast-conditioned medium (hGF-CM) has been considered a potential therapy for tissue regeneration due to its stability in maintaining multiple factors essential for tissue regeneration compared to live cell transplantation. This study aimed to investigate the potency of hGF-CM on stem cells from human dental pulp (DPSC) in pulp regeneration. A series of experiments confirmed that hGF-CM contributes to a significant increase in proliferation, migration capability, and cell viability of DPSC after H2O2 exposure. Moreover, it has been proved to facilitate the odontogenic differentiation of DPSC via qRT-PCR, ALP (alkaline phosphatase), and ARS (Alizarin Red S) staining. It has been discovered that such highly upregulated odontogenesis is related to certain types of ECM proteins (collagen and laminin) from hGF-CM via proteomics. In addition, it is found that the ERK pathway is a key mechanism via inhibition assay based on RNA-seq result. These findings demonstrate that hGF-CM could be beneficial biomolecules for pulp regeneration.

Investigating the Effects of Conditioned Media from Stem Cells of Human Exfoliated Deciduous Teeth on Dental Pulp Stem Cells

Pulp regeneration has recently attracted interest in modern dentistry. However, the success ratio of pulp regeneration is low due to the compromising potential of stem cells, such as their survival, migration, and odontoblastic differentiation. Stem cells from human exfoliated deciduous teeth (SHED) have been considered a promising tool for regenerative therapy due to their ability to secrete multiple factors that are essential for tissue regeneration, which is achieved by minimally invasive procedures with fewer ethical or legal concerns than those of other procedures. The aim of this study is to investigate the potency of SHED-derived conditioned media (SHED CM) on dental pulp stem cells (DPSCs), a major type of mesenchymal stem cells for dental pulp regeneration. Our results show the promotive efficiency of SHED CM on the proliferation, survival rate, and migration of DPSCs in a dose-dependent manner. Upregulation of odontoblast/osteogenic-related marker genes, such as ALP, DSPP, DMP1, OCN, and RUNX2, and enhanced mineral deposition of impaired DPSCs are also observed in the presence of SHED CM. The analysis of SHED CM found that a variety of cytokines and growth factors have positive effects on cell proliferation, migration, anti-apoptosis, and odontoblast/osteogenic differentiation. These findings suggest that SHED CM could provide some benefits to DPSCs in pulp regeneration.

Therapeutic application of chick early amniotic fluid: effective rescue of acute myocardial ischemic injury by intravenous administration

Myocardial regeneration has been considered a promising option for the treatment of adult myocardial injuries. Previously, a chick early amniotic fluid (ceAF) preparation was shown to contain growth-related factors that promoted embryonic growth and cellular proliferation, though the nature of the components within ceAF were not fully defined. Here we tested whether this ceAF preparation is similarly effective in the promotion of myocardial regeneration, which could provide an alternative therapeutic for intervening myocardial injury. In this study, a myocardial ischemic injury model was established in adult mice and pigs by multiple research entities, and we were able to show that ceAF can efficiently rescue damaged cardiac tissues and markedly improve cardiac function in both experimental models through intravenous administration. ceAF administration increased cell proliferation and improved angiogenesis, likely via down-regulation of Hippo-YAP signaling. Our data suggest that ceAF administration can effectively rescue ischemic heart injury, providing the key functional information for the further development of ceAF for use in attenuating myocardial injury.

Chitosan in association with osteogenic factors as a cell-homing platform for dentin regeneration: Analysis in a pulp-in-a-chip model

OBJECTIVE

In this paper we propose the association of β-glycerophosphate (βGP) and calcium-hydroxide with chitosan (CH) to formulate a porous bioactive scaffold suitable as a cell-homing platform for dentin regeneration.

METHODS

Calcium hydroxide and βGP solutions were incorporated into chitosan to modulate scaffold architecture and composition by a phase separation technique. Architecture, chemical composition, and degradability were evaluated, and biological characterizations were performed by the seeding of dental pulp cells (DPCs) onto scaffolds, or by cultivating them in contact with leachable components (extracts), to determine cytocompatibility and odontoblastic differentiation. Cell-free scaffolds were then positioned in intimate contact with a 3D culture of DPCs in a pulp-in-a-chip platform under simulated pulp pressure. Cell mobilization and odontoblastic marker expression were evaluated. Deposition of mineralized matrix was assessed in direct contact with dentin, in the absence of osteogenic factors.

RESULTS

Incorporation of calcium hydroxide and βGP generated a stable porous chitosan scaffold containing Ca-P nanoglobule topography (CH-Ca-βGP), which favored cell viability, alkaline phosphatase activity, and mineralized matrix deposition by cells seeded onto the scaffold structure and at a distance. The pulp-in-a-chip assay denoted its chemotactic and bioactive potential, since dentin sialoprotein-positive DPCs from 3D culture adhered to CH-Ca-βGP more than to plain chitosan. The higher deposition of mineralized matrix onto the scaffold and surrounding dentin was also observed.

SIGNIFICANCE

A CH-Ca-βGP scaffold creates a microenvironment capable of mobilizing DPC migration toward its structure, harnessing the odontogenic potential and culminating in the expression of a highly mineralizing phenotype, key factors for a cell-homing strategy.

Exosomes Secreted by Nucleus Pulposus Stem Cells Derived From Degenerative Intervertebral Disc Exacerbate Annulus Fibrosus Cell Degradation via Let-7b-5p

The pathogenesis of intervertebral disc degeneration (IDD) is complex and remains unclear. Nucleus pulposus stem cells (NPSCs) and annulus fibrosus cells (AFCs) play a critical role in the maintenance of intervertebral disc structure and function. Exosome-mediated miRNAs regulate cell proliferation, differentiation, apoptosis, and degradation. However, it is not clear whether the degenerative intervertebral disc-derived nucleus pulposus stem cells (D-NPSCs) can regulate the function of AFCs by delivering exosomes. Here, we show that exosomes secreted by nucleus pulposus stem cells derived from degenerative intervertebral disc (D-DPSC-exo) can exacerbate AFC degeneration via inhibiting cell proliferation, migration, matrix synthesis, and promoting apoptosis. Specifically, let-7b-5p was highly expressed in D-DPSC-exo. Transfection of let-7b-5p mimic was found to promote apoptosis and inhibit proliferation migration and matrix synthesis of AFCs. In addition, transfection with let-7b-5p inhibitor caused the effect of D-DPSC-exo on AFCs to be reversed. Furthermore, we found that D-DPSC-exo and let-7b-5p inhibited IGF1R expression and blocked the activation of the PI3K–Akt pathway. Results suggested that NPSC-exo exacerbated cell degeneration of AFCs via let-7b-5p, accompanied by inhibition of IGF1R expression, and PI3K–Akt pathway activation. Therefore, insights from this work may provide a clue for targeted molecular therapy of intervertebral disc degeneration.

Substrate coated with autologous decellularized extracellular matrix facilitates in vitro spreading of spheroid from adipose-derived stem cells through regulating ERK1/2-MMP2/9 pathway

Adipose-derived stem cells (ADSCs) are easily available and play an important role in regenerative medicine. In recent years, Cell spheroid models have been in the spotlight because of their various advantages and physiological proximity. Promoting the spreading of ADSCs spheroids may improve the therapeutic effect the transplanted ADSCs. In this study, we prepared autologous decellularized extracellular matrix (d-ECM) and ADSCs spheroids, and investigated in vitro spreading of the spheroids on the d-ECM-coated substrate. In addition, the effect of d-ECM powder (ECM-P) on the aggregation of ADSCs was analyzed in a three-dimensional (3D) culture system. The results showed that d-ECM accelerated the spreading of spheroids, and promoted the migration and proliferation of the surrounding monolayer cells, accompanied by ERK1/2 activation and an increase in the expression of MMP2 and MMP9. In addition, ECM-P facilitated the aggregation of free cells in 3D culture in a concentration-dependent way. The spheroid spreading and cell aggregation were both prevented by ERK1/2 selective inhibitor PD98059. Our data suggest that the d-ECM substrate and its derivant may regulate the transformation between ADSCs spheroids and the monolayer or free cells, and ERK1/2 signalling pathway may be involved in these processes.

Inhibition of exosomal miR-24-3p in diabetes restores angiogenesis and facilitates wound repair via targeting PIK3R3

Diabetic foot ulcer (DFU) is one of the common ailments of elderly people suffering from diabetes. Exosomes containing various active regulators have been found to play a significant role in apoptosis, cell proliferation and other biological processes. However, the effect and the underlying mechanism of action of diabetes patients derived from circulating exosomes (Dia-Exos) on DFU remain unclear. Herein, we aim to explore the potential regulatory role of Dia-Exos. First, we attempted to demonstrate the harmful effect of Dia-Exos both in vivo and in vitro. miRNA-24-3p (miR-24-3p) was found enriched with Dia-Exos. Hence, inhibition of this miRNA could partially reverse the negative effect of Dia-Exos, thus, in ture, accelerates wound repair. Luciferase assay further verified the binding of miR-24-3p to the 3'-UTR of phosphatidylinositol 3-kinase regulatory subunit gamma (PIK3R3) mRNA and the PIK3R3 expression enhanced human umbilical vein endothelial cells functionality in vitro. Hence, the findings of this study reveal the regulatory role of Dia-Exos in the process of wound healing and provide experimental evidence for the therapeutic effects of knocking down miR-24-3p in DFU treatment.