Comparative Assessment of Oral Mesenchymal Stem Cells Isolated from Healthy and Diseased Tissues

Mesenchymal stem cells derived from hard palate: An attractive alternative for regenerative medicine

OBJECTIVE

The palatal mucosa exhibits a notable ability to regenerate without causing scarring during the process of wound healing, rendering it a highly valuable reservoir of mesenchymal stem cells (MSCs). The aim of this review is to summarize the different sources of MSCs derived from hard palatal (PMSCs), thereby presenting a promising avenue for the utilization of regenerative medicine.

MATERIALS AND METHODS

Pertinent literatures focused on the sources, identification methods, and advantageous characteristics of PMSCs are obtained from PubMed and Web of Science.

RESULTS

PMSCs, originating from the hard palate periosteum, subepithelial adipose tissue, and lamina propria, have been successfully isolated and characterized, with positive markers for MSCs and negative markers for hematopoietic stem cells. Moreover, PMSCs demonstrate resistance to inflammatory stimuli, enabling uninterrupted osteogenesis in the presence of inflammation. Additionally, PMSCs possess a notable migratory capacity, facilitating prompt arrival at the site of injury. Furthermore, PMSCs exhibit various advantageous inherent in stem cells, including clonogenicity, self-renewal capability, and pluripotent differentiation potential.

CONCLUSIONS

PMSCs have stem cell-related properties and can be used for regenerative medicine of cells and tissues in the future.

Biomaterials derived from hard palate mucosa for tissue engineering and regenerative medicine

Autologous materials have superior biosafety and are widely used in clinical practice. Due to its excellent trauma-healing ability, the hard palate mucosa (HPM) has become a hot spot for autologous donor area research. Multiple studies have conducted an in-depth analysis of the healing ability of the HPM at the cellular and molecular levels. In addition, the HPM has good maneuverability as a donor area for soft tissue grafts, and researchers have isolated various specific mesenchymal stem cells (MSCs) from HPM. Free soft tissue grafts obtained from the HPM have been widely used in the clinic and have played an essential role in dentistry, eyelid reconstruction, and the repair of other specific soft tissue defects. This article reviews the advantages of HPM as a donor area and its related mechanisms, classes of HPM-derived biomaterials, the current status of clinical applications, challenges, and future development directions.

In Vitro Study of Composite Cements on Mesenchymal Stem Cells of Palatal Origin

Uniform filler distribution in composites is an important requirement. Therefore, BaO glass, nano hydroxyapatite and quartz filler distribution was realized through PCL microcapsules which progressively release filler during matrix polymerization. Two composites were realized based on a complex matrix containing BisGMA, UDMA, HEMA and PEG400 mixed with a previously described mineral filler: 33% for C1 and 31% for C2. The spreading efficiency was observed via SEM, revealing a complete disintegration of the microcapsules during C1 polymerization, while C2 preserved some microcapsule parts that were well embedded into the matrix beside BaO filler particles; this was confirmed by means of the EDS spectra. Mesenchymal stem cells of palatal origin were cultured on the composites for 1, 3, 5 and 7 days. The alkaline phosphatase (ALP) level was measured at each time interval and the cytotoxicity was tested after 3, 5 and 7 days of co-culture on the composite samples. The SEM investigation showed that both composites allowed for robust proliferation of the cells. The MSC cell pluripotency stage was observed from 1 to 3 days with an average level of ALP of 209.2 u/L for C1 and 193.0 u/L for C2 as well as a spindle cell morphology. Cell differentiation occurred after 5 and 7 days of culture, implied by morphological changes such as flattened, star and rounded shapes, observed via SEM, which were correlated with an increased ALP level (279.4 u/L for C1 and 284.3 u/L for C2). The EDX spectra after 7 days of co-culture revealed increasing amounts of P and Ca close to the hydroxyapatite stoichiometry, indicating the stimulation of the osteoinductive behavior of MSCs by C1 and C2. The MTT assay test showed a cell viability of 98.08% for C1 and 97.33% for C2 after 3 days, proving the increased biocompatibility of the composite samples. The cell viability slightly decreased at 5 and 7 days but the results were still excellent: 89.5% for C1 and 87.3% for C2. Thus, both C1 and C2 are suitable for further in vivo testing.

Regenerative Potential of Granulation Tissue in Periodontitis: A Systematic Review and Meta-analysis

Methods

Electronic searches were conducted in five databases including CENTRAL, MEDLINE, EMBASE, Web of Science, and Dentistry & Oral Sciences Source using a combination of MeSH terms and keywords up to 21 June 2022. Human studies including patients aged over 18 years with all forms of periodontitis were included. Following the risk of bias assessment, both qualitative and quantitative analyses were performed.

Results

A total of twelve studies were included in qualitative analysis and six of them in quantitative analyses. The evidence suggested that cells derived from periodontitis granulation tissue have osteogenic, adipogenic, chondrogenic, neurogenic, and angiogenic differentiation abilities as well as immunoregulatory properties. In particular, CD44⁺, CD73⁺, CD90⁺, CD105⁺, and CD146⁺ cells were found widely in granulation tissue whilst the only meta-analysis confirmed that CD90⁺ cells were present in lower numbers within the granulation tissue when compared with healthy periodontal tissue (WMD = -23.43%, 95% CI -30.43 to -16.44, p < 0.00001).

Conclusions

This review provided further evidence that granulation tissue from patients with periodontitis can be a potential stem cell source for regenerative therapy.

BMP-2 Delivery through Liposomes in Bone Regeneration

Bone regeneration is a central focus of maxillofacial research, especially when dealing with dental implants or critical sized wound sites. While bone has great regeneration potential, exogenous delivery of growth factors can greatly enhance the speed, duration, and quality of osseointegration, making a difference in a patient’s quality of life. Bone morphogenic protein 2 (BMP-2) is a highly potent growth factor that acts as a recruiting molecule for mesenchymal stromal cells, induces a rapid differentiation of them into osteoblasts, while also maintaining their viability. Currently, the literature data shows that the liposomal direct delivery or transfection of plasmids containing BMP-2 at the bone wound site often results in the overexpression of osteogenic markers and result in enhanced mineralization with formation of new bone matrix. We reviewed the literature on the scientific data regarding BMP-2 delivery with the help of liposomes. This may provide the ground for a future new bone regeneration strategy with real chances of reaching clinical practice.

Minimal influence of chronic inflammation on the potency and differentiation characteristics of gingiva-derived mesenchymal stem cells-An in vitro study

Objective:

Gingiva-derived mesenchymal stem cells (GMSCs) have been identified and characterized from healthy tissues. However, reports on the influence of chronic inflammation on their stemness characteristics are sparse. The present study evaluated the potency and differentiation ability of GMSCs from periodontally healthy GMSC (H-GMSC) and inflamed GMSC (I-GMSC) tissues.

Materials and Methods:

Established H-GMSCs and I-GMSCs were evaluated on their potency characteristics, such as morphology, viability, proliferation rate, population doubling time, colony-forming ability, expression of stemness markers, and mesenchymal differentiation potential.

Results:

H-GMSCs and I-GMSCs exhibited fibroblast-like morphology and showed >95% viability with high proliferation potential and shorter doubling time. H-GMSCs showed fewer and smaller colonies, whereas I-GMSCs exhibited multiple and larger colonies. The evaluation of stemness markers revealed that both H-GMSCs and I-GMSCs were weakly positive for stage-specific embryonic antigen-4, Stro1, and CD105 (Endoglin), strongly positive for CD73 and CD90, and negative for the hematopoietic cell markers, CD34 and CD45. H-GMSCs showed a slightly higher osteogenic potential when compared to I-GMSCs, while I-GMSCs had a higher adipogenic potential than H-GMSCs.

Conclusion:

The findings showed that the inflammatory environment might have a stimulatory effect on the growth kinetics and ability of colony formation in GMSCs. However, varied osteogenic and adipogenic differentiation was observed between H-GMSCs and I-GMSCs.

Injectable platelet-rich fibrin influences the behavior of gingival mesenchymal stem cells

In this study, we examined the effects of injectable platelet-rich fibrin (iPRF) on proliferation and osteodifferentiation in mesenchymal stem cells (MSCs) isolated from human gingiva. Gingival MSCs (gMSCs) were grown in experimental culture media with different concentrations of iPRF [5%, 10%, and replacement of fetal calf serum (FCS) in the standard media with 10% iPRF–10% iPRF-FCS]. Immunophenotyping of gMSCs was performed after seven days by flow cytometry, and their proliferation was examined after three and seven days using the Cell Counting Kit-8 method. After 14 days in culture, spontaneous osteogenic differentiation of gMSCs was evaluated via real-time polymerase chain reaction. All gMSCs were positive for cluster of differentiation (CD) 105, CD73, CD90, and CD44, and negative for CD34/45, CD14, CD79a, and human leukocyte antigen, DR isotype (HLA-DR). Reduced expression of some surface antigens was observed in the gMSCs grown in 10% iPRF-FCS medium compared to the other groups. After three days, gMSCs grown in 10% iPRF had proliferated significantly less than the other groups. After seven days, proliferation was significantly higher in the 5% iPRF cells compared to the control, while proliferation in the 10% iPRF and 10% iPRF-FCS groups was significantly lower. No spontaneous osteogenic differentiation was observed in the presence of iPRF, as observed by low runt-related transcription factor 2 (RUNX2) expression. Some expression of secreted protein acidic and cysteine rich (SPARC) and collagen 1 alpha (COL1A) was observed for all the gMSCs regardless of the culture medium composition. gMSCs grown in 10% iPRF had significantly lower SPARC expression. In conclusion, 5% iPRF stimulated gMSC proliferation, and an excessively high concentration of iPRF can impair osteogenic induction.

Analysis of cell-biomaterial interaction through cellular bridge formation in the interface between hGMSCs and CaP bioceramics

The combination of biomaterials and stem cells for clinical applications constitute a great challenge in bone tissue engineering. Hence, cellular networks derived from cells-biomaterials crosstalk have a profound influence on cell behaviour and communication, preceding proliferation and differentiation. The purpose of this study was to investigate in vitro cellular networks derived from human gingival mesenchymal stem cells (hGMSCs) and calcium phosphate (CaP) bioceramic interaction. Biological performance of CaP bioceramic and hGMSCs interaction was evaluated through cell adhesion and distribution, cellular proliferation, and potential osteogenic differentiation, at three different times: 5 h, 1 week and 4 weeks. Results confirmed that hGMSCs met the required MSCs criteria while displaying osteogenic differentiaton capacities. We found a significant increase of cellular numbers and proliferation levels. Also, protein and mRNA OPN expression were upregulated in cells cultured with CaP bioceramic by day 21, suggesting an osteoinductible effect of the CaP bioceramic on hGMSCs. Remarkably, CaP bioceramic aggregations were obtained through hGMSCs bridges, suggesting the in vitro potential of macrostructures formation. We conclude that hGMSCs and CaP bioceramics with micro and macropores support hGMSC adhesion, proliferation and osteogenic differentiation. Our results suggest that investigations focused on the interface cells-biomaterials are essential for bone tissue regenerative therapies.

Extracellular Matrix Composition and Remodeling: Current Perspectives on Secondary Palate Formation, Cleft Lip/Palate, and Palatal Reconstruction

Craniofacial development comprises a complex process in humans in which failures or disturbances frequently lead to congenital anomalies. Cleft lip with/without palate (CL/P) is a common congenital anomaly that occurs due to variations in craniofacial development genes, and may occur as part of a syndrome, or more commonly in isolated forms (non-syndromic). The etiology of CL/P is multifactorial with genes, environmental factors, and their potential interactions contributing to the condition. Rehabilitation of CL/P patients requires a multidisciplinary team to perform the multiple surgical, dental, and psychological interventions required throughout the patient's life. Despite progress, lip/palatal reconstruction is still a major treatment challenge. Genetic mutations and polymorphisms in several genes, including extracellular matrix (ECM) genes, soluble factors, and enzymes responsible for ECM remodeling (e.g., metalloproteinases), have been suggested to play a role in the etiology of CL/P; hence, these may be considered likely targets for the development of new preventive and/or therapeutic strategies. In this context, investigations are being conducted on new therapeutic approaches based on tissue bioengineering, associating stem cells with biomaterials, signaling molecules, and innovative technologies. In this review, we discuss the role of genes involved in ECM composition and remodeling during secondary palate formation and pathogenesis and genetic etiology of CL/P. We also discuss potential therapeutic approaches using bioactive molecules and principles of tissue bioengineering for state-of-the-art CL/P repair and palatal reconstruction.

Stem cell-like populations and immunoregulatory molecules in periodontal granulation tissue

BACKGROUND AND OBJECTIVES

Determine the presence of mesenchymal stem cells (MSCs) in healthy periodontal tissue and periodontal granulation tissue (GT) and explore associations between immuno-regulatory molecules and selected subgingival microorganisms.

MATERIAL AND METHODS

Mesenchymal stem cells were isolated, propagated and characterised by flow cytometry from a region of healthy gingival tissue and inflamed GT of 10 systemically healthy non-smokers with chronic periodontitis. Tissue levels of immunoregulatory molecules were determined by qPCR and Gingival Crevicular Fluid (GCF) levels by ELISA. Subgingival plaque levels of periodontal pathogens were determined by qPCR RESULTS: Cells with MSC-properties were isolated from both inflamed GT and healthy gingival (G) tissue. A pro-inflammatory process predominated in GT which was partly reflected in GCF and putative periodontal pathogens were higher at diseased sites. However, there was no significant difference in surface levels of mesenchymal (CD90, CD73, CD146, CD271, STRO-1), endothelial (CD105, CD106), hematopoietic (CD34, CD45) and embryonic (SSEA-4) stem cell markers between MSCs isolated from GT and G tissue.

CONCLUSION

Periodontal lesions, albeit inflamed, retain healing potential as inferred by the presence of MSC-like cells with similar immunophenotypic characteristics to those found in healthy periodontal tissue. Therefore, there might be merits for healing in preserving sufficient GT in-situ during periodontal surgery.

Applications of inflammation-derived gingival stem cells for testing the biocompatibility of dental restorative biomaterials

BACKGROUND

Normal or inflamed gingival tissues are regarded as a source of mesenchymal stem cells (MSCs) abundant and easily accessible through minimally invasive dental procedures. Due to the proximity of dental resin composites to gingival tissues and to the possible local cytotoxic effect of the eluted components, gingiva-derived MSCs could be used to investigate the biocompatibility of dental biomaterials.

PURPOSE

The present research aimed to isolate (MSCs) from inflamed and normal gingiva, to fully characterize them and to observe their behavior in relation with some commercial resin composite materials and one experimental material.

MATERIAL AND METHODS

Following their isolation, putative MSCs from both gingival sources were grown under the same culture conditions and characterized by immunophenotyping of cell surface antigens by flow-cytometry and transcription factors by immunocytochemical staining. Moreover, stemness gene expression was evaluated by RT-PCR analysis. Multipotent mesenchymal differentiation potential was investigated. Osteogenic and neurogenic differentiated cells were highlighted by immunocytochemical staining, chondrogenic cells by cytochemical staining, and adipocytes by cytochemical staining and spectrophotometry, respectively. Resin composite cytotoxicity was evaluated by cell membrane fluorescent labeling with PKH 26 and MTT assay. The results of PKH labeling were statistically analysed using two-way RM ANOVA with Bonferroni post-tests. For MTT assay, two-way RM ANOVA with Bonferroni post-tests and unpaired t test with Welch's correction were used.

RESULTS

A similar expression pattern of surface markers was observed. The cells were positive for CD105, CD73, CD90, CD49e, CD29, CD44 and CD166 and negative for CD45, CD34, CD14, CD79, HLA-DR and CD117 indicating a mesenchymal stem cell phenotype. The qRT-PCR analysis revealed a low gene expression for NOG, BMP4 and Oct3/4 and an increased expression for Nanog in both cells lines. Immunocytochemical analysis highlighted a more intense protein expression for Nanog, Oct3/4 and Sox-2 in MSCs derived from normal gingiva than from inflamed gingiva. Multipotent differentiation capacity of MSCs isolated from both sources was highlighted. The tested materials had no hazardous effect on MSCs as the two cell lines developed well onto resin composite substrates. Cell counting revealed some significant differences in the number of PKH-labeled MSCs at some experimental moments. Also, some differences in cell viability were recorded indicating better developmental conditions offered by some of the tested biomaterials.

CONCLUSIONS

The experimental resin composite behaved like the most biocompatible commercial material. Inflamed gingiva-derived MSCs retain their stem cell properties and could be used as a valuable cell line for testing dental biomaterials.

Cytotoxicity of Experimental Resin Composites on Mesenchymal Stem Cells Isolated from Two Oral Sources

Resin composite materials that are used to restore tooth cervical lesions associated with gingival recessions can hamper healing after root coverage surgeries. This study evaluates the in vitro cytotoxic effect of five resin composites (two commercial and three experimental) on oral mesenchymal stem cells (MSCs) and the persistence of stemness properties in high passage MSCs. Sorption and solubility tests were made for all materials. MSCs were isolated from re-entry palatal and periodontal granulation tissues and were characterized and cultured on composite discs. Cytotoxicity of the materials was evaluated by the Alamar Blue viability test, by Paul Karl Horan (PKH) labeling, and by immunocytochemical staining for actin. Water and saliva sorption and solubility data revealed that two of the experimental materials behaved comparable with the marketed resin composites. The Alamar Blue viability test shows that both cell lines grew well on composite discs that seemed to induce no apparent toxic effects. No signs of disruption of cytoskeleton organization was seen. Experimental resin composites can be recommended for further investigation for obtaining approval for use. The standard minimal criteria were fulfilled for high passage MSCs. Palatal tissue regains its regenerative properties in terms of MSC presence in the re-entry area after 6 months of healing.