Aging Donor-Derived Human Mesenchymal Stem Cells Exhibit Reduced Reactive Oxygen Species Loads and Increased Differentiation Potential Following Serial Expansion on a PEG-PCL Copolymer Substrate

PIK3R3 regulates differentiation and senescence of periodontal ligament stem cells and mitigates age-related alveolar bone loss by modulating FOXO1 expression

INTRODUCTION

Periodontal diseases are prevalent among middle-aged and elderly individuals. There's still no satisfactory solution for tooth loss caused by periodontal diseases. Human periodontal ligament stem cells (hPDLSCs) is a distinctive subgroup of mesenchymal stem cells, which play a crucial role in periodontal supportive tissues, but their application value hasn't been fully explored yet. As a regulatory subunit of PI3K, PIK3R3's role in stem cell regulation remains poorly comprehended.

OBJECTIVES

This study aims to explore the regulatory effect of PIK3R3 on differentiation and senescence of hPDLSCs and the underlying mechanism, as well as whether overexpression of PIK3R3 mitigate alveolar bone loss in aged rats.

METHODS

Human PDLSC lines with both PIK3R3 knockdown and overexpression are established. Osteogenic, adipogenic, chondrogenic and senescent induction are used to test the effect of PIK3R3 on senescence in vitro. Model of alveolar bone loss in aged mice is used to reveal the effect of PIK3R3 in vivo. FOXO1 siRNA is used for mechanism exploration.

RESULTS

Knockdown of PIK3R3 inhibits the mRNA and protein expression of markers in osteogenic, adipogenic, and chondrogenic differentiation of hPDLSCs but promotes in vitro senescence of hPDLSCs, including senescence markers expression, telomerase density and reactive oxygen species. Overexpression of PIK3R3 has the opposite effect. Furthermore, the result of Micro-CT and tissue section shows that overexpression of PIK3R3 in elder rats mitigates alveolar bone loss. Mechanistically, PIK3R3 regulates senescence of hPDLSCs through modulating FOXO1 expression. Expression of FOXO1 is altered when PIK3R3 is knocked down or overexpressed in senescent medium. Knockdown of FOXO1 promotes senescence of hPDLSCs and the senescence promoting effect of knocking down PIK3R3 is weakened when FOXO1 is highly expressed.

CONCLUSION

These findings indicate that PIK3R3 modulates senescence of hPDLSCs by regulating FOXO1 expression and shows promise as a therapeutic target for mitigating age-related alveolar bone loss.

Regulation Mechanisms and Maintenance Strategies of Stemness in Mesenchymal Stem Cells

Stemness pertains to the intrinsic ability of mesenchymal stem cells (MSCs) to undergo self-renewal and differentiate into multiple lineages, while simultaneously impeding their differentiation and preserving crucial differentiating genes in a state of quiescence and equilibrium. Owing to their favorable attributes, including uncomplicated isolation protocols, ethical compliance, and ease of procurement, MSCs have become a focal point of inquiry in the domains of regenerative medicine and tissue engineering. As age increases or ex vivo cultivation is prolonged, the functionality of MSCs decreases and their stemness gradually diminishes, thereby limiting their potential therapeutic applications. Despite the existence of several uncertainties surrounding the comprehension of MSC stemness, considerable advancements have been achieved in the clarification of the potential mechanisms that lead to stemness loss, as well as the associated strategies for stemness maintenance. This comprehensive review provides a systematic overview of the factors influencing the preservation of MSC stemness, the molecular mechanisms governing it, the strategies for its maintenance, and the therapeutic potential associated with stemness. Finally, we underscore the obstacles and prospective avenues in present investigations, providing innovative perspectives and opportunities for the preservation and therapeutic utilization of MSC stemness.

Patient Demographic Factors Are Not Associated With Mesenchymal Stromal Cell Concentration in Bone Marrow Aspirate Concentrate

Purpose

To describe the capacity for concentration of a single processing machine for bone marrow aspirate concentrate (BMAC) production and investigate the effects of demographic factors on the number of mesenchymal stromal cells (MSCs) in BMAC.

Methods

Patients enrolled in our institution's randomized control trials involving BMAC who had complete BMAC flow cytometry data were included. Multipotent MSC phenotype, defined as cell-surface coexpression of specific-identifying antigens (≥95% positive) and the absence of hematopoietic lineage markers (≤2% positive), was determined for both patient bone marrow aspirate (BMA) and BMAC samples. The ratio of cells in BMA:BMAC samples was calculated and Spearman correlations (i.e., body mass index [BMI]) and Kruskall-Wallis (i.e., age: <40, 40-60, >60 years) or Mann-Whitney (i.e., sex) tests were used to determine the relationship of cell concentration to demographic factors.

Results

Eighty patients were included in analysis (49% male, mean age: 49.9 ± 12.2 years). Mean concentration of BMA and BMAC was 2,048.13 ± 2,004.14 MSCs/mL and 5,618.87 ± 7,568.54 MSC/mL, respectively, with a mean BMAC:BMA ratio of 4.35 ± 2.09. A significantly greater MSC concentration was observed in the BMAC samples when compared with BMA (P = .005). No patient demographic factors (age, sex, height, weight, BMI) were found to predict MSC concentration in the BMAC samples (P ≥ .01).

Conclusions

Demographic factors, including age, sex, and BMI do not impact the final concentration of MSCs in BMAC when using a single harvest technique (anterior iliac crest) and a single processing system.

Clinical Relevance

As the role of BMAC therapy expands in clinical application, it becomes increasingly important to understand the determinants of BMAC composition and how it is affected by different harvesting techniques, concentrating processes, and patient demographics.

Exploring microenvironment strategies to delay mesenchymal stem cell senescence

Mesenchymal stem cells (MSCs) have recently emerged as an important candidate for cell therapy and tissue regeneration. However, some limitations in translational research and therapies still exist, such as insufficient cell supply, inadequate differentiation potential, and decreased immune capacity, all of which result from replicative senescence during long-term in vitro culture. In vitro, stem cells lack a protective microenvironment owing to the absence of physical and biochemical cues compared with the in vivo niche, which provides dynamic physicochemical and biological cues. This difference results in accelerated aging after long-term in vitro culture. Therefore, it remains a great challenge to delay replicative senescence in culture. Constructing a microenvironment to delay replicative senescence of MSCs by maintaining their phenotypes, properties, and functions is a feasible strategy to solve this problem and has made measurable progress both in preclinical studies and clinical trials. Here, we review the current knowledge on the characteristics of senescent MSCs, explore the molecular mechanisms of MSCs senescence, describe the niche of MSCs, and discuss some current microenvironment strategies to delay MSCs replicative senescence that can broaden their range of therapeutic applications.

Honey-incorporated nanofibre reduces replicative senescence of umbilical cord-derived mesenchymal stem cells

Umbilical cord-derived mesenchymal stem cells (UCDMSC) are attractive candidates for cell-based regenerative medicine. However, they are susceptible to replicative senescence during repetitive passaging for in-vitro expansion and induced senescence in an oxidative, inflammatory microenvironment in vivo. Aim of this study is to investigate if honey-incorporated matrices can be employed to reduce senescence of UCDMSC. Matrices were prepared by electrospinning solutions of honey with poly-vinyl alcohol (PVA). PVA:honey matrices exhibited free radical scavenging activity. Culture of UCDMSC on PVA:honey matrices showed improvement in cell proliferation compared to pure PVA nanofibres. Expression of vimentin indicated that mesenchymal phenotype is preserved after culturing on these matrices. Further, UCDMSC were serially subcultured and cells of two passages (P2 and P6) were evaluated for reactive oxygen species (ROS) load and senescence parameters. P6 cells showed a higher ROS load and β-galactosidase (β-gal) positive senescent cells compared to P2. However, culturing on PVA:honey substrates significantly reduced both ROS and β-gal markers compared to cells on PVA substrates. Honey contains several antioxidant and anti-inflammatory components, which can reduce the ROS-related senescence. Thus, it is concluded that honey containing nanofibres can be effective substrates for stem cell-based wound healing and regenerative medicine.

Human Mesenchymal Stem Cell Response to Lactoferrin-based Composite Coatings

The potential of mesenchymal stem cells (MSCs) for implantology and cell-based therapy represents one of the major ongoing research subjects within the last decades. In bone regeneration applications, the various environmental factors including bioactive compounds such as growth factors, chemicals and physical characteristics of biointerfaces are the key factors in controlling and regulating osteogenic differentiation from MSCs. In our study, we have investigated the influence of Lactoferrin (Lf) and Hydroxyapatite (HA) embedded within a biodegradable PEG-PCL copolymer on the osteogenic fate of MSCs, previous studies revealing an anti-inflammatory potential of the coating and osteogenic differentiation of murine pre-osteoblast cells. The copolymer matrix was obtained by the Matrix Assisted Pulsed Laser Evaporation technique (MAPLE) and the composite layers containing the bioactive compounds (Lf, HA, and Lf-HA) were characterised by Scanning Electron Microscopy and Atomic Force Microscopy. Energy-dispersive X-ray spectroscopy contact angle and surface energy of the analysed coatings were also measured. The characteristics of the composite surfaces were correlated with the viability, proliferation, and morphology of human MSCs (hMSCs) cultured on the developed coatings. All surfaces were found not to exhibit toxicity, as confirmed by the LIVE/DEAD assay. The Lf-HA composite exhibited an increase in osteogenic differentiation of hMSCs, results supported by alkaline phosphatase and mineralisation assays. This is the first report of the capacity of biodegradable composite layers containing Lf to induce osteogenic differentiation from hMSCs, a property revealing its potential for application in bone regeneration.