Assessment of an efficient xeno-free culture system of human periodontal ligament stem cells

Periodontal Ligament Stem Cell-Derived Exosomes Regulate Muc5ac Expression in Rat Conjunctival Goblet Cells via Regulating Macrophages Toward an Anti-Inflammatory Phenotype

BACKGROUND

Several studies have reported the protective effects of mesenchymal stem cell-derived exosomes (MSC-Exos) in reducing inflammation and decreasing conjunctival goblet cell (CGC) loss in dry eye disease. However, whether MSC-Exos provide anti-inflammatory profiles in macrophages, thus contributing to CGC protection, has remained elusive.

METHODS

Macrophages were incubated with PKH26-labeled periodontal ligament mesenchymal stem cell-derived exosomes (PDLSC-Exos) for 12 h, and uptake of PDLSC-Exos by macrophages was observed by a confocal fluorescence microscope. The mRNA expression of TNF-α, IL-10, and Arg1 was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of TNF-α and IL-10 were quantified using western blotting. Then, CGCs were exposed to different macrophage supernatants and qRT-PCR was used to detect the Muc5ac mRNA expression of CGCs in response to or absence of cholinergic stimulation. ELISA was used to determine the Muc5ac secretion of CGCs in response to cholinergic stimulation.

RESULTS

The uptake of PDLSC-Exos by M1 macrophages facilitates M2 macrophage polarization with the elevated expressions of IL-10 and Arg1. In macrophage supernatant-treated CGCs systems, PDLSC-Exo-treated M1 macrophage supernatant significantly enhanced the Muc5ac expression of CGCs in response to, or in the absence of, cholinergic stimulation, while the addition of PDLSC-Exos to the control macrophage supernatant did not generate a change in Muc5ac expression. Conversely, the addition of PDLSC-Exos to the diluted control macrophage supernatant induced a significant increase in Muc5ac expression.

CONCLUSION

PDLSC-Exos could protect CGCs against M1 macrophage-mediated inflammation, and the protective effects of PDLSC-Exos are partly attributable to their effects on M1 macrophages.

Osteogenic effect of crocin in human periodontal ligament stem cells via Wnt/β-catenin signaling

OBJECTIVES

Crocin is a major class of medicinal components in saffron. This study aimed to determine whether crocin directly promotes the proliferation and osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) in vitro and in vivo.

MATERIALS AND METHODS

CCK8 cell proliferation assay, reverse transcription quantitative polymerase chain reaction (RT-qPCR), Western blot analysis and Alizarin Red staining were performed in PDLSCs using crocin as a stimulant. DKK1 was used to selectively inhibit Wnt/β-catenin signaling, and Western blotting was performed to investigate the underlying mechanism. The PDLSCs were mixed with calcium phosphate cement and implanted into nude mice subcutaneously to study the effect of crocin on PDLSC osteogenic differentiation in vivo.

RESULTS

The CCK-8 assay showed that crocin did not promote the proliferation of PDLSCs. Treatment with 400 μM crocin significantly promoted PDLSC mRNA levels of ALP, COL1 and OCN; RUNX2 and BMP2 protein expression; mineralized nodule formation in vitro and in vivo; and ALP activity in tissues in vivo. In addition, crocin significantly promoted the phosphorylation of β-catenin and cyclin D1. DKK1 inhibits Wnt/β-catenin activation and partially reverses crocin-mediated promotion of PDLSC osteogenic differentiation.

CONCLUSION

Crocin may contribute to the regeneration of periodontal bone tissue.

Effects of Oral Cavity Stem Cell Sources and Serum-Free Cell Culture on Hydrogel Encapsulation of Mesenchymal Stem Cells for Bone Regeneration: An In Vitro Investigation

INTRODUCTION

To develop a stem cell delivery model and improve the safety of stem cell transplantation for bone regeneration, this study aimed to determine the effects of stem cell sources, serum-free cell culture, and hydrogel cell encapsulation on the growth and osteogenic differentiation of mesenchymal stem cells (MSCs) from the oral cavity.

METHODS

The study groups were categorized according to stem cell sources into buccal fat pad adipose (hBFP-ADSCs) (Groups 1, 4, and 7), periodontal ligament (hPDLSCs) (Groups 2, 5, and 8), and dental pulp-derived stem cells (hDPSCs) (Groups 3, 6, and 9). MSCs from each source were isolated and expanded in three types of sera: fetal bovine serum (FBS) (Groups 1-3), human serum (HS) (Groups 4-6), and synthetic serum (SS) (StemPro™ MSC SFM) (Groups 7-9) for monolayer (m) and hydrogel cell encapsulation cultures (e). Following this, the morphology, expression of MSC cell surface antigens, growth, and osteogenic differentiation potential of the MSCs, and the expression of adhesion molecules were analyzed and compared.

RESULTS

SS decreased variations in the morphology and expression levels of cell surface antigens of MSCs from three cell sources (Groups 7m-9m). The levels of osteoblastic differentiation of the hPDLSCs and hBFP-ADSCs were increased in SS (Groups 8m and 7m) and the cell encapsulation model (Groups 1e, 4e, 7e-9e), but the promoting effects of SS were decreased in a cell encapsulation model (Groups 7e-9e). The expression levels of the alpha v beta 3 (ITG-αVβ3) and beta 1 (ITG-β1) integrins in the encapsulated cells in FBS (Group 1e) were higher than those in the SS (Group 7e).

CONCLUSIONS

Human PDLSCs and BFP-ADSCs were the optimum stem cell source for stem cell encapsulation by using nanohydroxyapatite-calcium carbonate microcapsule-chitosan/collagen hydrogel in serum-free conditions.

Isolation and characterization of human periodontal ligament stem cells under the terms of use in clinical application: A pilot study

Background

The aim of the present study is to determine the possibility of isolation and characterization of the human periodontal ligament stem cells (hPDLSCs) using limited harvested periodontal ligament (PDL) tissue of only one patient's wisdom teeth (2-4 teeth) under the more compatible terms of use in clinical application without using the fetal bovine serum (FBS).

Materials and Methods

In this pilot study, hPDLSCs were isolated from the impacted third molar, and tissue was scraped from the roots of the impacted third molar of 10 volunteers to enzymatically digest using collagenase. The cells were sub-cultured. The samples of the first seven patients and half of the eighth patient's sample were cultured in alpha modified of Eagle's medium (α-MEM) (-FBS) medium and the other part of the eighth patient's sample was cultured with prior medium supplemented with +FBS 15% as a control of the cultivation protocol. While for the past two patients (9th and 10th the α-MEM medium was supplemented with L-Glutamine, anti/anti 2X, and 20% knock-out serum replacement (KSR). Two more nutritious supplements (N2 and B27) were added to the medium of the tenth sample. Flow-cytometric analysis for the mesenchymal stem cell surface markers CD105, CD45, CD90, and CD73 was performed. Subsequent polymerase chain reaction was undertaken on three samples cultured with two growth media.

Results

Cultivation failed in some of the samples because of the lack of cell adhesion to the culturing dish bottom (floating cells), but it was successful for the 9th and 10th patients, which were cultured in the α-MEM serum supplemented with KSR 20%. Flow cytometry analysis was positive for CD105, CD90, and CD73 and negative for CD45. The PDL stem cells (PDLSCs) expressed CD105, CD45, and CD90 but were poor for CD73.

Conclusion

According to the limited number of sample tests in this study, isolation and characterization of PDLSCs from collected PDL tissue of one patient's wisdom teeth (2-4) may be possible by the proper setup in synthetic FBS-free serum.

Effect of super activated platelet lysate on cell proliferation, repair and osteogenesis

BACKGROUND

Platelet lysate (PL) is considered as an alternative to fetal bovine serum (FBS) and facilitates the proliferation and differentiation of mesenchymal cells.

OBJECTIVE

The aim of this study is to explore whether super activated platelet lysate (sPL), a novel autologous platelet lysate, has the ability to inhibit inflammation and promote cell proliferation, repair and osteogenesis as a culture medium.

METHODS

Different concentrations of sPL on human fetal osteoblastic 1.19 cell line (hFOB1.19) proliferation and apoptotic repair were investigated; And detected proliferative capacity, inflammatory factor expressions and osteogenic differentiation of human dental pulp cells (hDPCs) stimulated by LPS under 10% FBS and 5% sPL mediums.

RESULTS

sPL promoted hFOB1.19 proliferation and had repairing effects on apoptotic cells. No significant difference in proliferation and IL-1α, IL-6 and TNF-α expressions of hDPCs in FBS and sPL medium stimulated by LPS. hDPCs in sPL osteogenic medium had higher osteogenic-related factor expressions and ALP activity. LPS promoted osteogenic-related factor expressions and ALP activity of hDPCs in FBS osteogenic medium, but opposite effect showed in sPL medium.

CONCLUSION

sPL promoted osteoblast proliferation and had restorative effects. Under LPS stimulation, sPL did not promote hDPCs proliferation or inhibit inflammation. sPL promotes osteogenic differentiation of hDPCs.

Brain Homogenate of a Rat Model of Alzheimer's Disease Modifies the Secretome of 3D Cultured Periodontal Ligament Stem Cells: A Potential Neuroregenerative Therapy

Background

Alzheimer's disease (AD) is a progressive neurodegenerative disease leading to neuronal cell death and manifested by cognitive disorders and behavioral impairment. Mesenchymal stem cells (MSCs) are one of the most promising candidates to stimulate neuroregeneration and prevent disease progression. Optimization of MSC culturing protocols is a key strategy to increase the therapeutic potential of the secretome.

Objectives

Here, we investigated the effect of brain homogenate of a rat model of AD (BH-AD) on the enhancement of protein secretion in the secretome of periodontal ligament stem cells (PDLSCs) when cultured in a 3D environment. Moreover, the effect of this modified secretome was examined on neural cells to study the impact of the conditioned medium (CM) on stimulation of regeneration or immunomodulation in AD.

Methods

PDLSCs were isolated and characterized. Then, the spheroids of PDLSCs were generated in a modified 3D culture plate. PDLSCs-derived CM was prepared in the presence of BH-AD (PDLSCs-HCM) and the absence of it (PDLSCs-CM). The viability of C6 glioma cells was assessed after exposure to different concentrations of both CMs. Then, a proteomic analysis was performed on the CMs.

Results

Differentiation into adipocytes and high expression of MSCs markers verified the precise isolation of PDLSCs. The PDLSC spheroids were formed after 7 days of 3D culturing, and their viability was confirmed. The effect of CMs on C6 glioma cell viability showed that both CMs at low concentrations (> 20 mg/mL) had no cytotoxic effect on C6 neural cells. The results showed that PDLSCs-HCM contains higher concentrations of proteins compared to PDLSCs-CM, including Src-homology 2 domain (SH2)-containing PTPs (SHP-1) and muscle glycogen phosphorylase (PYGM) proteins. SHP-1 has a role in nerve regeneration, and PYGM is involved in glycogen metabolism.

Conclusions

The modified secretome derived from 3D cultured spheroids of PDLSCs treated by BH-AD as a reservoir of regenerating neural factors can serve as a potential source for AD treatment.

Periodontal ligament stem cells as a promising therapeutic target for neural damage

BACKGROUND

The damaged neuronal cells of adult mammalian lack the regenerative ability to replace the neuronal connections. Periodontal ligament stem cells (PDLSCs) are the promising source for neuroregenerative applications that can improve the injured microenvironment of the damaged neural system. They provide neuronal progenitors and neurotrophic, anti-apoptotic and anti-inflammatory factors. In this study, we aimed to comprehensively explore the various neuronal differentiation potentials of PDLSCs for application in neural regeneration therapy.

MAIN TEXT

PDLSCs have superior potential to differentiate into various neural-like cells through a dedifferentiation stage followed by differentiation process without need for cell division. Diverse combination of nutritional factors can be used to induce the PDLSCs toward neural lineage. PDLSCs when coupled with biomaterials could have significant implications for neural tissue repair. PDLSCs can be a new clinical research target for Alzheimer's disease treatment, multiple sclerosis and cerebral ischemia. Moreover, PDLSCs have beneficial effects on retinal ganglion cell regeneration and photoreceptor survival. PDLSCs can be a great source for the repair of injured peripheral nerve through the expression of several neural growth factors and differentiation into Schwann cells.

CONCLUSION

In conclusion, these cells are an appealing source for utilizing in clinical treatment of the neuropathological disorders. Although significant in vitro and in vivo investigations were carried out in order for neural differentiation evaluation of these cells into diverse types of neurons, more preclinical and clinical studies are needed to elucidate their therapeutic potential for neural diseases.

Optimizing large-scale autologous human keratinocyte sheets for major burns-Toward an animal-free production and a more accessible clinical application

Background and Aims

Autologous keratinocyte sheets constitute an important component of the burn wound treatment toolbox available to a surgeon and can be considered a life‐saving procedure for patients with severe burns over 50% of their total body surface area. Large‐scale keratinocyte sheet cultivation still fundamentally relies on the use of animal components such as inactivated murine 3T3 fibroblasts as feeders, animal‐derived enzymes such as trypsin, as well as media components such as fetal bovine serum (FBS). This study was therefore aimed to optimize autologous keratinocyte sheets by comparing various alternatives to critical components in their production.

Methods

Human skin samples were retrieved from remnant operative tissues. Cell isolation efficiency and viability were investigated by comparing the efficacy of porcine‐derived trypsin and animal‐free enzymes (Accutase and TrypLESelect). The subsequent expansion of the cells and the keratinocyte sheet formation was analyzed, comparing various cell culture substrates (inactivated murine 3T3 fibroblasts, inactivated human fibroblasts, Collagen I or plain tissue culture plastic), as well as media containing serum or chemically defined animal‐free media.

Results

The cell isolation step showed clear cell yield advantages when using porcine‐derived trypsin, compared to animal‐free alternatives. The keratinocyte sheets produced using animal‐free serum were similar to those produced using 3T3 feeder layer and FBS‐containing medium, particularly in mechanical integrity as all grafts were liftable. In addition, sheets grown on collagen in an animal‐free medium showed indications of advantages in homogeneity, speed, reduced variability, and differentiation status compared to the other growth conditions investigated. Most importantly, the procedure was compatible with the up‐scaling requirements of major burn wound treatments.

Conclusion

This study demonstrated that animal‐free components could be used successfully to reduce the risk profile of large‐scale autologous keratinocyte sheet production, and thereby increase clinical accessibility.

Human Platelet Lysate Maintains Stemness of Umbilical Cord-Derived Mesenchymal Stromal Cells and Promote Lung Repair in Rat Bronchopulmonary Dysplasia

Mesenchymal stromal cells (MSCs) show potential for treating preclinical models of newborn bronchopulmonary dysplasia (BPD), but studies of their therapeutic effectiveness have had mixed results, in part due to the use of different media supplements for MSCs expansion in vitro. The current study sought to identify an optimal culture supplement of umbilical cord-derived MSCs (UC-MSCs) for BPD therapy. In this study, we found that UC-MSCs cultured with human platelet lysate (hPL-UCMSCs) were maintained a small size from Passage 1 (P1) to P10, while UC-MSCs cultured with fetal bovine serum (FBS-UCMSCs) became wide and flat. Furthermore, hPL was associated with lower levels of senescence in UC-MSCs during in vitro expansion compared with FBS, as indicated by the results of β-galactosidase staining and measures of senescence-related genes (CDKN2A, CDKN1A, and mTOR). In addition, hPL enhanced the proliferation and cell viability of the UC-MSCs and reduced their doubling time in vitro. Compared with FBS-UCMSCs, hPL-UCMSCs have a greater potential to differentiate into osteocytes and chondrocytes. Moreover, using hPL resulted in greater expression of Nestin and specific paracrine factors (VEGF, TGF-β1, FGF2, IL-8, and IL-6) in UC-MSCs compared to using FBS. Critically, we also found that hPL-UCMSCs are more effective than FBS-UCMSCs for the treatment of BPD in a rat model, with hPL leading to improvements in survival rate, lung architecture and fibrosis, and lung capillary density. Finally, qPCR of rat lung mRNA demonstrated that hPL-UCMSCs had lower expression levels of inflammatory factors (TNF-α and IL-1β) and a key chemokine (MCP-1) at postnatal day 10, and there was significant reduction of CD68⁺ macrophages in lung tissue after hPL-UCMSCs transplantation. Altogether, our findings suggest that hPL is an optimal culture supplement for UC-MSCs expansion in vitro, and that hPL-UCMSCs promote lung repair in rat BPD disease.

Pluripotency of Dental Pulp Cells and Periodontal Ligament Cells Was Enhanced through Cell-Cell Communication via STAT3/Oct-4/Sox2 Signaling

Alternation in culture environment due to cell-cell communications can rejuvenate the biological activity of aged/differentiated cells and stimulate the expression of pluripotency markers. Dental pulp cells (DPCs) and periodontal ligament cells (PDLCs) are promising candidates in dental tissue regeneration. However, the molecular network that underlies cell-cell communications between dental-derived cells and the microenvironment remains to be identified. To elucidate the signaling network that regulates the pluripotency of DPCs and PDLCs, proliferation, apoptosis, cell cycle, and the expression of Oct-4/Sox2/c-Myc in DPCs and PDLCs with indirect/direct coculture were examined. PCR arrays were constructed to identify genes that were differentially expressed, and the results were confirmed by a rat model with injury. Further research on the mechanism of the related signaling pathways was investigated by overexpression/silence of STAT3, ChIP, the dual-luciferase reporter assay, and EMSA. We found that the proliferation and apoptosis of DPCs and PDLCs were inhibited, and their cell cycles were arrested at the G0/G1 phase after coculture. Oct-4, Sox2, and STAT3 expression significantly increased and PAX5 expression decreased in the coculture systems. Oct-4/Sox2/STAT3/PAX5 was actively expressed in the rat defect model. Moreover, STAT3 was directly bound to the Oct-4 and Sox2 gene promoter regions and activated the expression of those genes. Our data showed that the pluripotency of DPCs and PDLCs was enhanced through cell-cell communication. STAT3 plays essential roles in regulating the pluripotency of DPCs and PDLCs by targeting Oct-4 and Sox2 both in vitro and in vivo.

Type I collagen facilitates safe and reliable expansion of human dental pulp stem cells in xenogeneic serum-free culture

BACKGROUND

Human dental pulp stem cells (DPSCs) are a readily accessible and promising cell source for regenerative medicine. We recently reported that a xenogeneic serum-free culture medium (XFM) is preferable to fetal bovine serum-containing culture medium for ex vivo expansion of DPSCs; however, we observed that, upon reaching overconfluence, XFM cells developed a multilayered structure and frequently underwent apoptotic death, resulting in reduced cell yield. Therefore, we focused on optimization of the XFM culture system to avoid the undesirable death of DPSCs.

METHODS

We selected type I collagen (COL) as the optimal coating substrate for the cultureware and compared DPSCs cultured on COL in XFM (COL-XFM cells) to the conventional XFM cultures (XFM cells).

RESULTS

Our results demonstrated that COL coating facilitated significantly higher rates of cell isolation and growth; upon reaching overconfluence, cell survival and sustained proliferative potential resulted in two-fold yield compared to the XFM cells. Surprisingly, after subculturing the overconfluent COL-XFM cultures, the cells retained stem cell behavior including stable cell growth, multidifferentiation potential, stem cell phenotype, and chromosomal stability, which was achieved through HIF-1α-dependent production and uniform distribution of collagen type I and its interactions with integrins α2β1 and α11β1 at overconfluency. In contrast, cells undergoing apoptotic death within overconfluent XFM cultures had disorganized mitochondria with membrane depolarization.

CONCLUSION

The use of COL as a coating substrate promises safe and reliable handling of DPSCs in XFM culture, allowing translational stem cell medicine to achieve stable isolation, expansion, and banking of donor-derived stem cells.

The effect of platelet lysate in culture of PDLSCs: an in vitro comparative study

Background

Cellular therapy clinical applications require large-scale production of stem cells. Therefore, abundance, ease of isolation, and proliferative potential are the most important factors in choosing the appropriate source of cells for transplantation studies. Multipotent stem cells obtained from periodontal ligament (PDL) can be used in periodontal tissue regeneration. In this study, we aimed to evaluate and compare the characteristics of periodontal ligament stem cells (PDLSCs), extracted by either enzymatic digestion or explant methods, and expanded using two different serum types: fetal bovine serum (FBS) and xeno-free platelet lysate (PL).

Methods

Expanded PDLSCs were assessed for their proliferation capacity, surface markers expression, colony formation, differentiation potential and ability to self-renewal. Most importantly, PDLSCs were evaluated for their ability to produce osteoblasts in vitro.

Results

PDLSCs isolated by explant method and expanded in PL serve as a promising source of stem cells for osteoblasts regeneration. These cells showed higher proliferation capacity, they retained their stemness characteristics throughout the passages and they revealed an increase in the expression level of osteogenic markers, without showing any karyotypic abnormalities after cell expansion.

Conclusions

PDLSCs produced using explant extraction method and expanded in cell culture media supplemented with PL provide an excellent source of xeno-free cells for the generation of functional osteoblasts.

Periodontal Ligament Stem Cells: Current Knowledge and Future Perspectives

Teeth represent a fascinating area of study in regenerative medicine, because of their unique and complex developmental origin. Several types of mesenchymal stem cells (MSCs) have been characterized in the oral cavity, and those derived from the periodontal ligament (PDL) first isolated by our group in 2005, can be expanded in a xeno-free medium preserving morphological features and markers associated with pluripotency. These postnatal MSCs can be easily recovered by noninvasive procedures and cultured. This could facilitate the use of adult stem cells in human clinical regeneration therapy. In this review we summarize the results of our studies describing morphofunctional features, surface markers, and multilineage differentiation capacity in vitro of PDL MSCs obtained in our laboratories. In vivo characterization of PDL stem cell (PDLSC) location and heterogeneity are still lacking. However, we describe studies exploring the potential use of PDLSC to treat both periodontal diseases and regeneration of other tissues. These MSCs may have an advantage in possessing also angiogenetic, immunoregulatory, and anti-inflammatory properties. The secretome of such cells contains several interesting molecules mimicking the effects of the producer cells. We describe some recent studies from our group on the use of conditioned medium from PDL MSCs, and purified extracellular vesicles therein contained, in animal models of experimental autoimmune encephalomyelitis and their potential application to human disease.

Effects of lysophosphatidic acid on human periodontal ligament stem cells from teeth extracted from dental patients

Despite their potential applications in future regenerative medicine, periodontal ligament stem cells (PDLSCs) are difficult to obtain in large amounts from patients. Therefore, maintaining stemness while expanding the cell numbers for medical use is the key to transitioning PDLSCs from the bench to the clinic. Lysophosphatidic acid (LPA), which is present in the human body and saliva, is a signaling molecule derived from phospholipids. In this study, we examined the effects of LPA on stemness maintenance in human PDLSCs. Several spindle-shaped and fibroblast-like periodontal ligament stem-like cell lines were established from PDLSC isolation. Among these cell lines, the most morphologically appropriate cell line was characterized. The expression levels of OCT4, NANOG (a stem cell marker), and CD90 (a mesenchymal stem cell marker) were high. However, CD73 (a negative marker of mesenchymal stem cells) expression was not observed. Notably, immunofluorescence analysis identified the expression of STRO-1, CD146 (a mesenchymal stem cell marker), and sex determining region Y-box 2 at the protein level. In addition, lipid droplets were stained by Oil red O after the induction of adipogenesis for 21 days, and mineralized nodules were stained by Alizarin Red S after the induction of osteogenesis for 14 days. Alkaline phosphate staining also demonstrated the occurrence of osteogenesis. In summary, we established a human PDLSC line, which could be applied as a cell source for tissue regeneration in dental patients. However, further studies are needed to determine the detailed effects of LPA on PDLSCs.

Comparative effect of platelet-rich plasma, platelet-poor plasma, and fetal bovine serum on the proliferative response of periodontal ligament cell subpopulations

OBJECTIVES

Cell-based therapies involve the need to expand cell cultures ex vivo for their subsequent implantation in an autologous manner. An important limitation regarding this technology is the use of fetal bovine serum (FBS) that has critical safety limitations. Platelet-derived fractions represent an autologous source of growth factors that may be used for the expansion of these cell cultures. Periodontal ligament (PDL) cells comprise a heterogeneous cell population that may not necessarily respond in a uniform manner to proliferative stimuli. The aim of this study was to evaluate the ability of two platelet-derived fractions, platelet-rich plasma (PRP) and platelet-poor plasma (PPP) and FBS on the proliferative response of different subpopulations of PDL cell cultures.

MATERIALS AND METHODS

PDL cells were characterized and then exposed to PRP, PPP, or FBS during 2, 5, or 14 days to analyze cell proliferation and clonogenic capability. Cell proliferation was evaluated through immunofluorescence for Ki67 and by tracing carboxyfluorescein diacetate succinimidyl ester (CFSE) dye in combination with mesenchymal stem cell markers using flow cytometry.

RESULTS

Both PRP and PPP stimulated PDL cell proliferation and their clonogenic ability. We found a significant increase of CD73- and CD90-positive cells after PRP or PPP treatment, compared to FBS. Otherwise, no differences were found regarding the response of CD146-or CD105-positive cells when stimulated with PRP, PPP, or FBS.

CONCLUSION

PRP and PPP can stimulate the proliferation and clonogenicity of PDL cell populations including cells positive for CD90 and CD73 markers.

CLINICAL RELEVANCE

These findings may have implications for future therapies aiming to stimulate periodontal regeneration using autologous growth factors.

From "Bench to Bedside": Current Advancement on Large-Scale Production of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are the primary cell source in cell therapy and regenerative medicine due to its extraordinary self-renewing capacity and multilineage differentiation potential. Clinical trials involving MSCs are being conducted in a range of human diseases and the number of registered cases is continuously increasing. However, a wide gap exists between the number of MSCs obtainable from the donor site and the number required for implantation to damage tissues, and also between MSC scalability and MSC phenotype stability. The clinical translation of MSCs necessitates a scalable expansion bioprocess for the biomanufacturing of therapeutically qualified cells. This review presents current achievements for expansion of MSCs. Issues involving culture condition modification, bioreactor systems, as well as microcarrier and scaffold platforms for optimal MSC systems are discussed. Most importantly, the gap between current MSC expansion and clinical application, as well as outbreak directions for the future are discussed. The present systemic review will bring new insights into future large-scale MSC expansion and clinical application.

Venous Blood Derivatives as FBS-Substitutes for Mesenchymal Stem Cells: A Systematic Scoping Review

Although the biological properties of mesenchymal stem cells (MSC) are well-characterized in vitro, MSC clinical application is still far away to be achieved, mainly due to the need of xenogeneic substances for cell expansion, such as fetal bovine serum (FBS). FBS presents risks regarding pathogens transmissions and internalization of animal's proteins, which can unleash antigenic responses in patients after MSC implantation. A wide range of venous blood derivatives (VBD) has been reported as FBS substitutes showing promising results. Thus, the aim of this study was to conduct a systematic scoping review to analyze whether VBD are effective FBS substitutes for MSC ex vivo expansion. The search was performed in SciVerse ScopusTM, PubMed, Web of ScienceTM, BIREME, Cochrane library up to January 2016. The keywords were selected using MeSH and entry terms. Two independent reviewers scrutinized the records obtained considering specific inclusion criteria. The included studies were evaluated in accordance with a modified Arksey and O' Malley's framework. From 184 found studies, 90 were included. Bone marrow mesenchymal stem cells (BMMSC) were presented in most of these studies. Overall, VBD allowed for either, maintenance of MCS's fibroblast-like morphology, high proliferation, high colony-formation ability and maintenance of multipotency. Besides. MSC expanded in VBD supplements presented higher mitogen activity than FBS. VBD seems to be excellent xeno-free serum for ex vivo expansion of mesenchymal stem cells. However, an accentuated heterogeneity was observed between the carried out protocols for VBD isolation did not allowing for direct comparisons between the included studies.

Strategies for MSC expansion and MSC-based microtissue for bone regeneration

Mesenchymal stem cells (MSCs) have gained increasing attention as a potential approach for the treatment of bone injuries due to their multi-lineage differentiation potential and also their ability to recognize and home to damaged tissue sites, secreting bioactive factors that can modulate the immune system and enhance tissue repair. However, a wide gap between the number of MSCs obtainable from the donor site and the number required for implantation, as well as the lack of understanding of MSC functions under different in vitro and in vivo microenvironment, hinders the progression of MSCs toward clinical settings. The clinical translation of MSCs pre-requisites a scalable expansion process for the biomanufacturing of therapeutically qualified cells. This review briefly introduces the features of implanted MSCs to determine the best strategies to optimize their regenerative capacity, as well as the current MSC implantation for bone diseases. Current achievements for expansion of MSCs using various culturing methods, bioreactor technologies, biomaterial platforms, as well as microtissue-based expansion strategies are also discussed, providing new insights into future large-scale MSC expansion and clinical applications.

Conditioned medium from human gingival mesenchymal stem cells protects motor-neuron-like NSC-34 cells against scratch-injury-induced cell death

Neuronal cell death is a normal process during central nervous system (CNS) development and is also involved in the death of motor neurons in diverse spinal motor neuron degenerative diseases. Here, we investigated the neuroprotective effect of secretory factors released from human gingival mesenchymal stem cells (hGMSCs) in mechanically injured murine motor-neuron-like NSC-34 cells. The cells were exposed to scratch injury and the markers for apoptosis and oxidative stress were examined. Immunocytochemistry results showed that proapoptotic markers cleaved caspase-3 and Bax were elevated while anti-apoptotic protein Bcl-2 was suppressed in scratch-injured NSC-34 cells. Oxidative stress markers SOD-1, inducible nitric oxide synthase (iNOS), Cox-2, and proinflammatory cytokine tumor necrosis factor alpha (TNF-α) were activated. Conditioned medium (CM) derived from hGMSCs (hGMSC-CM) significantly blocked the cell death by suppressing SOD-1, iNOS, TNF-α, cleaved caspase-3, and Bax. Bcl-2 and anti-inflammatory cytokine anti-interleukin 10 (IL-10) were increased in hGMSC-CM-treated injured cells. Moreover, hGMSC-CM treatment upregulated neurotrophins anti-brain-derived neurotrophic factor (BDNF) and NT3. Western blot data of hGMSC-CM revealed the presence of neurotrophins nerve growth factor (NGF), NT3, anti-inflammatory cytokines IL-10, and transforming growth factor beta (TGF-β), suggesting their positive role to elicit neuroprotection. Our results propose that hGMSC-CM may serve as a simple and potential autologous therapeutic tool to treat motor neuron injury.

MyD88/ERK/NFkB pathways and pro-inflammatory cytokines release in periodontal ligament stem cells stimulated by Porphyromonas gingivalis

The present study was aimed at investigating whether human Periodontal Ligament Stem Cells (hPDLSCs) were capable of sensing and reacting to lipopolysaccharide from Porphyromonas gingivalis (LPS-G) which is widely recognized as a major pathogen in the development and progression of periodontitis. At this purpose hPDLCs were stimulated with 5 μg/mL LPS-G at various times and the expression of toll-like receptor 4 (TLR4) was evaluated. Toll-like receptors (TLRs) play an essential role in innate immune signaling in response to microbial infections, and in particular TLR4, type-I transmembrane proteins, has been shown recognizing LPS-G. Our results put in evidence, in treated samples, an overexpression of TLR4 indicating that, hPDLSCs express a functional TLR4 receptor. In addition, LPS-G challenge induces a significant cell growth decrease starting from 24 h until 72 h of treatment. LPS-G leads the activation of the TLR4/MyD88 complex, triggering the secretion of proinflammatory cytokines cascade as: IL-1α, IL-8, TNF-α and β and EOTAXIN. Moreover, the upregulation of pERK/ERK signaling pathways and NFkB nuclear translocation was evident. On the basis of these observations, we conclude that hPDLSCs could represent an appropriate stem cells niche modeling leading to understand and evaluate the biological mechanisms of periodontal stem cells in response to LPS-G, mimicking in vitro an inflammatory process occurring in vivo in periodontal disease.

Conditioned medium from relapsing-remitting multiple sclerosis patients reduces the expression and release of inflammatory cytokines induced by LPS-gingivalis in THP-1 and MO3.13 cell lines

The present research was aimed at evaluating the effect of the conditioned medium (CM) from human periodontal ligament stem cells (hPDLSCs) obtained from healthy donors (hPDLSCs-CM) and from Relapsing-Remitting Multiple Sclerosis patients (RR-MS-CM) on inflammatory response induced by Porphyromonas gingivalis lipopolysaccharide (LPS-G) in a monocytoid human cell line (THP-1) and human oligodendrocyte cell line (MO3.13). Human periodontal ligament biopsies were carried out from control donor patients and selected RR-MS donors. Sample tissues were obtained from premolar teeth during root scaling and subsequently cultured. The effect of hPDLSCs-CM and RR-MS-CM on cell viability in PMA differentiated THP-1 (as a model of microglia) was measured using a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assay. The same experiments were performed in undifferentiated and differentiated MO3.13 cells used as models of progenitor cells and oligodendrocytes, respectively. The expression of tumor necrosis factor alpha (TNF)-α, interleukin (IL)-1β and IL-6 was evaluated by Real-Time Polymerase Chain Reaction (RT-PCR), and enzyme-linked immunosorbent assay (ELISA). The expression level of the Toll-like receptor 4 (TLR-4), for which LPS-G is a ligand, was evaluated by Western blot analysis. The results were analyzed by ANOVA using Graph Pad Prism software. LPS-G significantly increased TNFα, IL-1β and IL-6 mRNA expression and protein levels in the differentiated THP-1 cells and oligodendrocyte MO3.13 progenitor cells. Treatment with hPDLSCs-CM or with RR-MS-CM significantly attenuated the LPS-induced expression and production of these pro-inflammatory cytokines. The CM from both healthy donors and RR-MS patients also reduced the LPS-G stimulated protein levels of TLR-4 in differentiated THP-1 cells. On the whole our data add new evidence on the anti-inflammatory effects of these peculiar stem cells even when derived from RR-MS patients and open novel perspectives in the therapeutic use of autologous periodontal stem cells in neuroinflammatory/neurodegenerative diseases including MS.

Stemness Maintenance Properties in Human Oral Stem Cells after Long-Term Passage

Background. Neural crest-derived mesenchymal stem cells (MSCs) from human oral tissues possess immunomodulatory and regenerative properties and are emerging as a potential therapeutic tool to treat diverse diseases, such as multiple sclerosis, myocardial infarction, and connective tissue damages. In addition to cell-surface antigens, dental MSCs express embryonic stem cell markers as neural crest cells originate from the ectoderm layer. In vitro passages may eventually modify these embryonic marker expressions and other stemness properties, including proliferation. In the present study, we have investigated the expression of proteins involved in cell proliferation/senescence and embryonic stem cell markers during early (passage 2) and late passages (passage 15) in MSCs obtained from human gingiva, periodontal, and dental pulp tissues. Methods. Cell proliferation assay, beta galactosidase staining, immunocytochemistry, and real-time PCR techniques were applied. Results. Cell proliferation assay showed no difference between early and late passages while senescence markers p16 and p21 were considerably increased in late passage. Embryonic stem cell markers including SKIL, MEIS1, and JARID2 were differentially modulated between P2 and P15 cells. Discussion. Our results suggest that the presence of embryonic and proliferation markers even in late passage may potentially endorse the application of dental-derived MSCs in stem cell therapy-based clinical trials.

Role of Cortico-Cancellous Heterologous Bone in Human Periodontal Ligament Stem Cell Xeno-Free Culture Studied by Synchrotron Radiation Phase-Contrast Microtomography

This study was designed to quantitatively demonstrate via three-dimensional (3D) images, through the Synchrotron Radiation Phase-Contrast Microtomography (SR-PhC-MicroCT), the osteoinductive properties of a cortico-cancellous scaffold (Osteobiol Dual Block—DB) cultured with human Periodontal Ligament Stem Cells (hPDLSCs) in xeno-free media. In vitro cultures of hPDLSCs, obtained from alveolar crest and horizontal fibers of the periodontal ligament, were seeded onto DB scaffolds and cultured in xeno-free media for three weeks. 3D images were obtained by SR-PhC-microCT after one and three weeks from culture beginning. MicroCT data were successively processed with a phase-retrieval algorithm based on the Transport of Intensity Equation (TIE). The chosen experimental method, previously demonstratively applied for the 3D characterization of the same constructs in not xeno-free media, quantitatively monitored also in this case the early stages of bone formation in basal and differentiating conditions. Interestingly, it quantitatively showed in the xeno-free environment a significant acceleration of the mineralization process, regardless of the culture (basal/differentiating) medium. This work showed in 3D that the DB guides the osteogenic differentiation of hPDLSCs in xeno-free cultures, in agreement with 2D observations and functional studies previously performed by some of the authors. Indeed, here we fully proved in 3D that expanded hPDLSCs, using xeno-free media formulation, not only provide the basis for Good Manufacturing Practice (preserving the stem cells’ morphological features and their ability to differentiate into mesenchymal lineage) but have to be considered, combined to DB scaffolds, as interesting candidates for potential clinical use in new custom made tissue-engineered constructs.

Periodontal tissue engineering: current strategies and the role of platelet rich hemoderivatives

Periodontal tissue engineering procures to regenerate the periodontal tissue assuring the right combination of scaffolds, biochemical cues and cells. The platelet rich hemoderivatives might provide the adequate growth factors and structural proteins for the predictable regeneration of periodontium.

Cannabidiol Activates Neuronal Precursor Genes in Human Gingival Mesenchymal Stromal Cells

In the last years, mesenchymal stromal cells (MSCs) from oral tissues have received considerable interest in regenerative medicine since they can be obtained with minimal invasive procedure and exhibit immunomodulatory properties. This study was aimed to investigate whether in vitro pre-treatment of MSCs obtained from human gingiva (hGMSCs) with Cannabidiol (CBD), a cannabinoid component produced by the plant Cannabis sativa, may promote human gingiva derived MSCs to differentiate toward neuronal precursor cells. Specifically, we have treated the hGMSCs with CBD (5 µM) for 24 h in order to evaluate the expression of genes involved in cannabidiol signaling, cell proliferation, self-renewal and multipotency, and neural progenitor cells differentiation. Next generation sequencing (NGS) demonstrated that CBD activates genes associated with G protein coupled receptor signaling in hGMSCs. Genes involved in DNA replication, cell cycle, proliferation, and apoptosis were regulated. Moreover, genes associated with the biological process of neuronal progenitor cells (NCPs) proliferation, neuron differentiation, neurogenesis, and nervous system development were significantly modulated. From our results, we hypothesize that human gingiva-derived MSCs conditioned with CBD could represent a valid method for improving the hGMSCs phenotype and thus might be a potential therapeutic tool in the treatment of neurodegenerative diseases. J. Cell. Biochem. 118: 1531-1546, 2017. © 2016 Wiley Periodicals, Inc.

The secretome of periodontal ligament stem cells from MS patients protects against EAE

Manipulation of stem cells or stem cells-derived secretome has emerged as a novel alternative therapeutic option for multiple sclerosis (MS). Here we show that human periodontal ligament stem cells (hPDLSCs)-derived conditioned medium (hPDLSCs-CM) and purified exosomes/microvesicles (hPDLSCs-EMVs) obtained from Relapsing Remitting (RR)-MS patients and healthy donors block experimental autoimmune encephalomyelitis (EAE), a mouse model of MS, by inducing anti-inflammatory and immunosuppressive effects in spinal cord and spleen, and reverse disease progression by restoring tissue integrity via remyelination in the spinal cord. We show that hPDLSCs-CM and hPDLSCs-EMVs reduce pro-inflammatory cytokines IL-17, IFN-γ, IL-1β, IL-6, TNF-α, and induce anti-inflammatory IL-10. In addition, apoptosis related STAT1, p53, Caspase 3, and Bax expressions were attenuated. Our findings unravel the immunosuppressive effects of hPDLSCs-CM and hPDLSCs-EMVs in EAE mice, and suggest simple alternative autologous source for patient-customized cell-free targeting treatment in MS patients.

Gingival Stromal Cells as an In Vitro Model: Cannabidiol Modulates Genes Linked With Amyotrophic Lateral Sclerosis

Research in recent years has extensively investigated the therapeutic efficacy of mesenchymal stromal cells in regenerative medicine for many neurodegenerative diseases at preclinical and clinical stages. However, the success rate of stem cell therapy remains less at translational phase. Lack of relevant animal models that potentially simulate the molecular etiology of human pathological symptoms might be a reason behind such poor clinical outcomes associated with stem cell therapy. Apparently, self-renewal and differentiation ability of mesenchymal stem cells may help to study the early developmental signaling pathways connected with the diseases, such as Alzheimer's disease, Amyotrophic lateral sclerosis (ALS), etc., at in vitro level. Cannabidiol, a non-psychotrophic cannabinoid, has been demonstrated as a potent anti-inflammatory and neuroprotective agent in neurological preclinical models. In the present study, we investigated the modulatory role of cannabidiol on genes associated with ALS using human gingiva-derived mesenchymal stromal cells (hGMSCs) as an in vitro model system. Next generation transcriptomic sequencing analysis demonstrated considerable modifications in the expression of genes connected with ALS pathology, oxidative stress, mitochondrial dysfunction, and excitotoxicity in hGMSCs treated with cannabidiol. Our results suggest the efficacy of cannabidiol to delineate the unknown molecular pathways, which may underlie ALS pathology at an early stage using hGMSCs as a compelling in vitro system. J. Cell. Biochem. 118: 819-828, 2017. © 2016 Wiley Periodicals, Inc.

Cannabidiol Modulates the Immunophenotype and Inhibits the Activation of the Inflammasome in Human Gingival Mesenchymal Stem Cells

Human Gingival Mesenchymal Stem Cells (hGMSCs) are multipotential cells that can expand and differentiate in culture under specific and standardized conditions. In the present study, we have investigated whether in vitro pre-treatment of hGMSCs with Cannabidiol (CBD) can influence their expression profile, improving the therapeutic potential of this cell culture. Following CBD treatment (5 μM) for 24 h, gene expression analysis through Next Generation Sequencing (NGS) has revealed several genes differentially expressed between CBD-treated hGMSCs (CBD-hGMSCs) and control cells (CTR-hGMSCs) that were linked to inflammation and apoptosis. In particular, we have demonstrated that CBD treatment in hGMSCs prevented the activation of the NALP3-inflammasome pathway by suppressing the levels of NALP3, CASP1, and IL18, and in parallel, inhibited apoptosis, as demonstrated by the suppression of Bax. CBD treatment was also able to modulate the expression of the well-known mesenchymal stem cell markers (CD13, CD29, CD73, CD44, CD90, and CD166), and other surface antigens. Specifically, CBD led to the downregulation of genes codifying for antigens involved in the activation of the immune system (CD109, CD151, CD40, CD46, CD59, CD68, CD81, CD82, CD99), while it led to the upregulation of those implicated in the inhibition of the immune responses (CD47, CD55, CD276). In conclusion, the present study will provide a new simple and reproducible method for preconditioning hGMSCs with CBD, before transplantation, as an interesting strategy for improving the hGMSCs molecular phenotype, reducing the risk of immune or inflammatory reactions in the host, and in parallel, for increasing their survival and thus, their long-term therapeutic efficacy.

Conditioned medium of periodontal ligament mesenchymal stem cells exert anti-inflammatory effects in lipopolysaccharide-activated mouse motoneurons

Conditioned medium derived from mesenchymal stem cells (MSCs) shows immunomodulatory and neuroprotective effects in preclinical models. Given the difficulty to harvest MSCs from bone marrow and adipose tissues, research has been focused to find alternative resources for MSCs, such as oral-derived tissues. Recently, we have demonstrated the protective effects of MSCs obtained from healthy human periodontal ligament tissue (hPDLSCs) in murine experimental autoimmune encephalomyelitis model. In the present in vitro study, we have investigated the immunomodulatory and neuroprotective effects of conditioned medium obtained from hPDLSCs of Relapsing Remitting- Multiple sclerosis (RR-MS) patients on NSC34 mouse motoneurons stimulated with lipopolysaccharide (LPS). Immunocytochemistry and western blotting were performed. Increased level of TLR4 and NFκB, and reduced level of IκB-α were observed in LPS-stimulated motoneurons, which were modulated by pre-conditioning with hPDLSC-conditioned medium. Inflammatory cytokines (TNF-α, IL-10), neuroprotective markers (Nestin, NFL 70, NGF, GAP43), and apoptotic markers (Bax, Bcl-2, p21) were modulated. Moreover, extracellular vesicles of hPDLSC-conditioned medium showed the presence of anti-inflammatory cytokines IL-10 and TGF-β. Our results demonstrate the immunosuppressive properties of hPDLSC-conditioned medium of RR-MS patients in motoneurons subjected to inflammation. Our findings warrant further preclinical and clinical studies to elucidate the autologous therapeutic efficacy of hPDLSC-conditioned medium in neurodegenerative diseases.

Immobilization and delivery of biologically active Lipoxin A4 using electrospinning technology

Lipoxin (LX)A₄ is a lipoxygenase-formed arachidonic acid metabolite with potent anti-inflammatory, pro-resolution properties. Its therapeutic efficacy has been largely demonstrated in a variety of cellular, preclinical and clinical models. Among these, periodontal disease, where LXA₄ promotes tissue repair, also by modulating functions of human periodontal ligament stem cells (hPDLSCs). As medicated biomembranes may be particularly useful in clinical settings, where local stimulation of tissue repair is needed, we used electrospinning to embed LXA₄ in membranes made of poly(ethylene oxide) (PEO) and poly(d,l-lactide) (PDLLA). These membranes were fully characterized by scanning electron microscopy, differential scanning calorimetry and biocompatibility with hPDLSCs. Here, we report that LXA₄ is retained in these membranes and that ∼15-20% of the total LXA₄ amount added to the reaction can be eluted from the membranes using an aqueous buffered medium. The eluted LXA₄ fully retained its capability to stimulate hPDLSC proliferation. A similar effect was obtained by adding directly the LXA₄-containing membranes to cells. These results demonstrate for the first time that LXA₄ can be incorporated into biomembranes, which may be useful to combat local inflammation and promote tissue repair in selected clinical settings.

Nuclear translocation of PKCα isoenzyme is involved in neurogenic commitment of human neural crest-derived periodontal ligament stem cells

Stem cells isolated from human adult tissue niche represent a promising source for neural differentiation. Human Periodontal Ligament Stem Cells (hPDLSCs) originating from the neural crest are particularly suitable for induction of neural commitment. In this study, under xeno-free culture conditions, in undifferentiated hPDLSCs and in hPDLSCs induced to neuronal differentiation by basic Fibroblast Growth Factor, the level of some neural markers have been analyzed. The hPDLSCs spontaneously express Nestin, a neural progenitor marker. In these cells, the neurogenic process induced to rearrange the cytoskeleton, form neurospheres and express higher levels of Nestin and Tyrosine Hydroxylase, indicating neural induction. Protein Kinase C (PKC) is highly expressed in neural tissue and has a key role in neuronal functions. In particular the Ca(2+) and diacylglycerol-dependent activation of PKCα isozyme is involved in the regulation of neuronal differentiation. Another main component of the pathways controlling neuronal differentiation is the Growth Associated Protein-43 (GAP-43), whose activity is strictly regulated by PKC. The aim of this study is to investigate the role of PKCα/GAP-43 nuclear signal transduction pathway during neuronal commitment of hPDLSCs. During hPDLSCs neurogenic commitment the levels of p-PKC and p-GAP-43 increased both in cytoplasmic and nuclear compartment. PKCα nuclear translocation induced GAP-43 movement to the cytoplasm, where it is known to regulate growth cone dynamics and neuronal differentiation. Moreover, the degree of cytosolic Ca(2+) mobilization appeared to be more pronounced in differentiated hPDLSCs than in undifferentiated cells. This study provides evidences of a new PKCα/GAP-43 nuclear signalling pathway that controls neuronal differentiation in hPDLSCs, leading the way to a potential use of these cells in cell-based therapy in neurodegenerative diseases.

Effects of short-term inflammatory and/or hypoxic pretreatments on periodontal ligament stem cells: in vitro and in vivo studies

In this study, we extensively screened the in vitro and in vivo effects of PDLSCs following short-term inflammatory and/or hypoxic pretreatments. We found that the 24-h hypoxic pretreatment of PDLSCs significantly enhanced cell migration and improved cell surface CXCR4 expression. In addition, hypoxia-pretreated PDLSCs exhibited improved cell colony formation and proliferation. Cells that were dually stimulated also formed more colonies compared to untreated cells but their proliferation did not increase. Importantly, the hypoxic pretreatment of PDLSCs enhanced cell differentiation as determined by elevated RUNX-2 and ALP protein expression. In this context, the inflammatory stimulus impaired cell OCN protein expression, while dual stimuli led to decreased RUNX-2 and OCN mRNA levels. Although preconditioning PDLSCs with inflammatory and/or hypoxic pretreatments resulted in no differences in the production of matrix proteins, hypoxic pretreatment led to the generation of thicker cell sheets; the inflammatory stimulus weakened the ability of cells to form sheets. All the resultant cell sheets exhibited clear bone regeneration following ectopic transplantation as well as in periodontal defect models; the amount of new bone formed by hypoxia-preconditioned cells was significantly greater than that formed by inflammatory stimulus- or dual-stimuli-treated cells or by nonpreconditioned cells. The regeneration of new cementum and periodontal ligaments was only identified in the hypoxia-stimulus and no-stimulus cell groups. Our findings suggest that PDLSCs that undergo short-term hypoxic pretreatment show improved cellular behavior in vitro and enhanced regenerative potential in vivo. The preconditioning of PDLSCs via combined treatments or an inflammatory stimulus requires further investigation.

Platelet lysate supports the in vitro expansion of human periodontal ligament stem cells for cytotherapeutic use

Human platelet lysate (PL) produced under optimal conditions of standardization and safety has been increasingly suggested as the future 'gold standard' supplement to replace fetal bovine serum (FBS) for the ex vivo propagation of mesenchymal stem cells for translational medicine and cell therapy applications. However, the multifaceted effects of PL on tissue-specific stem cells remain largely unexplored. In the present study, we investigated the stem cell behaviours of human periodontal ligament stem cells (PDLSCs) in media with or without PL. Our data indicate that human PL, either as an adjuvant for culture media or as a substitute for FBS, supports the proliferation and expansion of human PDLSCs derived from either 'young' or 'old' donors to the same extent as FBS, without interfering with their immunomodulatory capacities. Although PL appears to inhibit the in vitro differentiation of 'young' or 'old' PDLSCs, their decreased osteogenic potential may be restored to similar or higher levels compared with FBS-expanded cells. PL- and FBS-expanded PDLSCs exhibited a similar potential to form mineralized nodules and expressed similar levels of osteogenic genes. Our data indicate that large clinically relevant quantities of PDLSCs may be yielded by the use of human PL; however, further analysis of its precise composition and function will pave the way for determining optimized, defined culture conditions. In addition to the potential increase in patient safety, our findings highlight the need for further research to develop the potential of PL-expanded PDLSCs for clinical use. Copyright © 2016 John Wiley & Sons, Ltd.

Recombinant Xeno-Free Vitronectin Supports Self-Renewal and Pluripotency in Protein-Induced Pluripotent Stem Cells

Patient safety is a major concern in the application of induced pluripotent stem cells (iPSCs) in cell-based therapy. Efforts are being made to reprogram, maintain, and differentiate iPSCs in defined conditions to provide a safe source of stem cells for regenerative medicine. Recently, human fibroblasts were successfully reprogrammed into pluripotent stem cells using four recombinant proteins (OCT4, c-Myc, KLF4, and SOX2) fused with a cell-penetrating peptide (9R). These protein-induced pluripotent stem cells (piPSCs) are maintained and propagated on a feeder layer of mouse embryonic fibroblasts. Use of animal-derived products in maintenance and differentiation of iPSCs poses risks of zoonotic disease transmission and immune rejection when transplanted into humans. To avoid potential incorporation of xenogenic products, we cultured piPSCs on recombinant human matrix proteins. We then tested whether recombinant human matrix proteins can support self-renewal and pluripotency of piPSCs. After long-term culture on recombinant human vitronectin in xeno-free conditions, piPSCs retained the expression of pluripotent markers. The pluripotency of these cells was further evaluated by differentiating toward ectoderm, mesoderm, and endoderm lineages in vitro. In conclusion, recombinant human vitronectin can support the long-term culture and maintain the stemness of piPSCs in defined nonxenogenic conditions.

Alternative source of stem cells derived from human periodontal ligament: a new treatment for experimental autoimmune encephalomyelitis

Background

Multiple sclerosis is a demyelinating disease mostly of autoimmune origin that affects and damages the central nervous system, leading to a disabling condition. The aim of the present study was to investigate whether administration of mesenchymal stem cells from human periodontal ligament (hPDLSCs) could ameliorate multiple sclerosis progression by exerting neuroprotective effects in an experimental model of autoimmune encephalomyelitis (EAE).

Methods

EAE was induced by immunization with myelin oligodendroglial glycoprotein peptide (MOG)_35–55 in C57BL/6 mice. After immunization, mice were observed every 48 hours for signs of EAE and weight loss. At the onset of disease, approximately 14 days after immunization, EAE mice were subjected to a single intravenous injection of hPDLSCs (10⁶ cells/150 μl) into the tail vein. At the point of animal sacrifice on day 56 after EAE induction, spinal cord and brain tissues were collected in order to perform histological evaluation, immunohistochemistry and western blotting analysis.

Results

Achieved results reveal that treatment with hPDLSCs may exert neuroprotective effects against EAE, diminishing both clinical signs and histological score typical of the disease (lymphocytic infiltration and demyelination) probably through the production of neurotrophic factors (results focused on brain-derived neurotrophic factor and nerve growth factor expression). Furthermore, administration of hPDLSCs modulates expression of inflammatory key markers (tumor necrosis factor-α, interleukin (IL)-1β, IL-10, glial fibrillary acidic protein, Nrf2 and Foxp3), the release of CD4 and CD8α T cells, and the triggering of apoptotic death pathway (data shown for cleaved caspase 3, p53 and p21).

Conclusions

In light of the achieved results, transplantation of hPDLSCs may represent a putative novel and helpful tool for multiple sclerosis treatment. These cells could have considerable implication for future therapies for multiple sclerosis and this study may represent the starting point for further investigations.

Human Periodontal Stem Cells Release Specialized Proresolving Mediators and Carry Immunomodulatory and Prohealing Properties Regulated by Lipoxins

The actions of human periodontal ligament stem cells (hPDLSCs) on polymorphonuclear neutrophil (PMN) apoptosis and antimicrobial functions, and the impact of lipoxin A₄ (LXA₄) on hPDLSCs were investigated. hPDLSCs significantly reduced apoptosis and stimulated microbicidal activity of human PMNs, via both cell-cell interactions and paracrine mechanisms. hPDLSCs also were found to biosynthesize proresolving lipid mediators and prostaglandins. This study also demonstrated that the LXA₄-ALX/FPR2 axis regulates regenerative functions of hPDLSCs by a novel receptor-mediated mechanism.

Unresolved inflammation and tissue destruction are underlying mechanisms of periodontitis, which is linked to dysregulated polymorphonuclear neutrophil (PMN) functions. Lipoxin A₄ (LXA₄) is a specialized proresolving lipid mediator (SPM) that dampens excessive inflammation, promotes resolution, and protects from leukocyte-mediated tissue damage. Human periodontal ligament stem cells (hPDLSCs) represent key players during tissue regeneration and may contribute to resolution of inflammation; thus, they may represent a promising tool in regenerative dentistry. In the present study, we investigated the actions of hPDLSCs on PMN apoptosis and antimicrobial functions, and determined the impact of LXA₄ on hPDLSCs. hPDLSCs significantly reduced apoptosis and stimulated microbicidal activity of human PMNs, via both cell-cell interactions and paracrine mechanisms. Lipid mediator metabololipidomics analysis demonstrated that hPDLSCs biosynthesize SPMs, including resolvin D1, D2, D5, and D6; protectin D1; maresins; and LXB₄; as well as prostaglandins D₂, E₂, and F_2α. LXA₄ significantly enhanced proliferation, migration, and wound healing capacity of hPDLSCs through the activation of its cognate receptor ALX/FPR2, expressed on hPDLSCs. Together, these results demonstrate that hPDLSCs modulate PMN functions, and provide the first evidence that stem cells generate SPM and that the LXA₄-ALX/FPR2 axis regulates regenerative functions of hPDLSCs by a novel receptor-mediated mechanism.

Significance

These findings uncovered unappreciated features of stem cells from the periodontal ligament, supporting the notion that these cells may act as master regulators of pathophysiological events through the release of mediators that promote the resolution of inflammation and bacterial killing. The study also demonstrated that it is possible to modulate important functions of periodontal stem cells using lipoxin A₄, a potent endogenous stop signal of inflammation. Thus, this study revealed an unappreciated anti-inflammatory proregenerative circuit that may be exploited to combat periodontal pathologies using resident stem cells. Moreover, the data may represent a more general template to explain the immunomodulatory functions of stem cells.

Osteogenic potential of dualblocks cultured with human periodontal ligament stem cells: in vitro and synchrotron microtomography study

BACKGROUND AND OBJECTIVE

In the present study, the early stages of in vitro bone formation in collagenated porcine scaffolds cultured with human periodontal ligament cells were investigated. The comparison between the osteogenic potential of this structure in basal and differentiating culture media was explored to predict the mechanism of its biological behavior as graft in human defect. Results were validated by synchrotron radiation X-Ray phase contrast computed microtomography (micro-CT). As the periodontal disease plays a key role in systemic and oral diseases, it is crucial to find advanced therapeutic clinical interventions to repair periodontal defects. This has been recently explored using cells and tissues developed in vitro that should ideally be immunologically, functionally, structurally and mechanically identical to the native tissue.

MATERIAL AND METHODS

In vitro cultures of human periodontal ligament cells, easily obtained by scraping of alveolar crestal and horizontal fibers of the periodontal ligament, were seeded on to collagenated porcine blocks constituted by natural cancellous and cortical bone. 3D images were obtained by synchrotron radiation micro-CT and processed with a phase-retrieval algorithm based on the transport of intensity equation.

RESULTS

Starting from the second week of culture, newly formed mineralized bone was detected in all the scaffolds, both in basal and differentiating media. Bone mineralization was proved to occur preferentially in the trabecular portion and in differentiating media.

CONCLUSION

The chosen method, supported by phase contrast micro-CT analysis, successfully and quantitatively monitored the early stages of bone formation and the rate of the bioscaffold resorption in basal and differentiating culture media.

Periodontal ligament stem cells: current status, concerns, and future prospects

Periodontal ligament stem cells (PDLSCs), which reside in the perivascular space of the periodontium, possess characteristics of mesenchymal stem cells and are a promising tool for periodontal regeneration. Recently, great progress has been made in PDLSC transplantation. Investigators are attempting to maximize the proliferation and differentiation potential of PDLSCs by modifying culture conditions and applying growth factors. Nevertheless, problems remain. First, incomparability among different studies must be minimized by establishing standard guidelines for culture and identification of PDLSCs. Notably, attention should be paid to the biological safety of PDLSC transplantation. The present review updates the latest findings regarding PDLSCs and discusses standard criteria for culture and identification of PDLSCs. Finally, the review calls for careful consideration of PDLSC transplantation safety.