Cell Source For Tissue Engineering Research Articles

THE ROLE OF PERICYTES IN BONE TISSUE REGENERATION AND THERAPEUTIC APPLICATIONS

The regeneration of massive bone defects poses a significant challenge in traumatology and orthopedics, often requiring bone grafting procedures following tumor resection, surgery, or severe injury. Current treatment methods include autologous and allogeneic bone grafts, as well as bone substitutes. While autologous transplantation is considered the standard, it is limited by donor site morbidity and availability. Allogeneic transplantation presents risks such as graft rejection and disease transmission. Bone substitutes may not fully restore bone defects. Tissue-engineered biomaterials offer promise for effective regeneration, utilizing stem cells, growth factors, and scaffolds. Adipose tissue, rich in mesenchymal stem cells and perivascular stem cells (pericytes), is a promising cell source for tissue engineering. This thesis explores the therapeutic potential of pericytes combined with various biological carriers and stimulating factors to enhance bone tissue regeneration. Pericytes, contractile cells surrounding small blood vessels, are crucial for vessel integrity and blood flow regulation. They express markers like α-SMA and PDGFR-β and participate in angiogenesis, immune function, and tissue repair. Interactions with endothelial cells via signaling pathways involving molecules like VEGF and TGF-β are vital for vessel formation and stability. With their multipotent nature, pericytes show promise for regenerative medicine. Ongoing research is essential to address challenges in pericyte biology, including identification and understanding their roles in tissue regeneration. Studies highlight the potential of adipose tissue-derived pericytes in bone regeneration, particularly CD146+ pericytes, showing efficacy in spinal fusion and nonunion fracture treatment when combined with DBM. Preclinical studies confirm their effectiveness, especially when incorporated into various scaffold materials. Clinical studies using adipose-derived stem cells and autologous microfragmented adipose tissue have shown promise, with pericyte-enriched fractions holding potential for improved outcomes. Future research into pericyte application, combined with growth factors and scaffolds, could significantly advance bone tissue regeneration and regenerative medicine. Human pericytes show promise for bone tissue regeneration due to their mesenchymal stem cell properties and role in vascular stabilization. Injectable hydrogels are crucial for bone tissue engineering, with various biomaterials developed for this purpose. Studies using injectable hydrogels with pericytes have demonstrated their efficacy in accelerating bone regeneration in different models. Further advancements in injectable hydrogel technology incorporating stem cells and osteoinductive factors are needed for more efficient bone tissue restoration.

A Review of 3D Bioprinting Technologies in the Reconstruction of Human Nasal Cartilaginous Tissue

Background Frequent nose defects due to inborn causes or accidents have increased the demand for rhinoplasty. In addition to a functional defect, nose defects are also known as aesthetic defects because the shape of the nose is one of the most prominent features that define the human face. Hence, common reconstruction methods could not meet the requirements caused by limitations. Objective This study investigates the ability of different three-dimensional bioprinting methods to repair defects in the nose area. Methods In this review study, articles available in ScienceDirect, Springer, Wiley, Cambridge, De Gruyter, and Google Scholar databases were used. The search was done using the following keywords: Tissue engineering, nasal cartilage, 3D bioprinting, and bioink materials. The search was done with a time limit of the last 4 years. Out of 300 eligible articles, 159 articles were finally reviewed. Results Bioprinting has special potential for repairing nasal cartilaginous tissue. Hydrogels have become an excellent option for mimicking the microenvironment of the host tissue due to their porosity and ability to load different materials, as well as their ability to absorb water and encapsulate cells. On the other hand, the two main cell sources for tissue engineering of nasal cartilage are autologous chondrocytes and mesenchymal stem cells. Conclusion Bioprinting technology can bio-mimic the cartilage host tissue to an acceptable degree morphologically, biochemically, and mechanically to be implanted surgically. Although the use of bioprinting at the clinical level still faces limitations, the prospect of this technology is promising since it can fix nasal defects with low cost, unique accuracy, and personalization.

Effect of in vivo culture conditions on the proliferation and differentiation of rat adipose-derived stromal cells

Adipose-derived stromal cells (ADSCs) are promising stem cell sources for tissue engineering and cell-based therapy. However, long-term in vitro expansion of ADSCs impedes stemness maintenance, which is partly attributed to deprivation of their original microenvironment. Incompetent cells limit the therapeutic effects of ADSC-based clinical strategies. Therefore, reconstructing a more physiologically and physically relevant niche is an ideal strategy to address this issue and therefore facilitates the extensive application of ADSCs. Here, we transplanted separated ADSCs into local subcutaneous adipose tissues of nude mice as an in vivo cell culture model. We found that transplanted ADSCs maintained their primitive morphology and showed improved proliferation and delayed senescence compared to those of cells cultured in an incubator. Significantly increased expression of stemness-related markers and multilineage differentiation abilities were further observed in in vivo cultured ADSCs. Finally, sequencing revealed that genes whose expression differed between ADSCs obtained under in vivo and in vitro conditions were mainly located in the extracellular matrix and extracellular space and that these genes participate in regulating transcription and protein synthesis. Moreover, we found that an Egr1 signaling pathway might exert a crucial impact on controlling stemness properties. Our findings might collectively pave the way for ADSC-based applications.

Isolation of Murine Adipose-Derived Stromal/Stem Cells Using an Explant Culture Method.

Adipose tissue provides a valuable cell source for tissue engineering, regenerative medicine, and adipose tissue biology studies. The most widely used adipose-derived stromal/stem cells (ASCs) isolation protocol involves enzymatic digestion with collagenase. However, the yield of the method often proves to bepoor if not impossiblefor collection of sufficient stromal vascular fraction (SVF) for expansion when the sample size is small, for instance whenonly newborn mice are available for cell culture. Here, we describe an efficient protocol for the isolation and expansion of ASCs using explant cultureas an alternative. Briefly, adipose tissue was minced after removing excess liquid. Then, the minced tissue was placed in culture dishes or flasks. The cells will migrate out of tissue and adhere to the culture surface after one or more days.

Potentiality of Bone Marrow-Derived Mesenchymal Stromal Cells (BM-MSCs) to Differentiate into the Osteogenic Lineage in in Vitro Model of Tissue Regeneration

Introduction:The mesenchymal stromal cells (MSCs) have gained considerable popularity owing to the vast possibilities and lack of ethical constraints. MSCs serve as multipotent progenitors for several niche components in the bone marrow (BM) and play an essential role in the quiescence, proliferation, and differentiation of hematopoietic stem cells. Recently, MSCs from BM (BM-MSCs) represent an attractive cell source for tissue engineering, thanks to their immunomodulatory property, self-renewing and high proliferative capability. BM-MSCs have multi-lineages (adipogenesis, chondrogenesis, osteogenesis) potential and in combination with biomaterials, well support cell-attachments and stimulate extracellular matrix synthesis. For these reasons, BM-MSCs have a great potential for regenerative medicine applications. The present research aims to evaluate the ability of BM-MSCs to proliferate and differentiate toward the osteogenic lineage into innovative three-dimensional bioresorbable scaffold based on gelatin-chitosan hydrogel with a poly(lactic acid) lattice structure (PLA-CH) for regenerative medicine applications in the presence of fetal bovine serum (FBS) or human platelet lysate (HPL) with or without the osteogenic medium (OM). Methods: BM-MSCs were expanded to the passages 3 or 4 and seeded into the PLA-CH, in dry state, at a cellular density of 7x10 5 cells/scaffolds in growth medium (GM). For inducing osteogenic differentiation, cells/scaffolds constructs were cultured in 24-well plates for 4 weeks with OM consisting of a high-glucose DMEM supplemented with 10% FBS or 5% HPL, 10 −7M Dex, 25 mg/ml l-ascorbic acid, and 3mM NaH 2PO 4. For histomorphological analysis at optical microscope, scaffolds were embedded in paraffin using an automatic processor Donatello series 2 (Diapath S.p.A., Bergamo, Italy). Serial paraffin sections (5 µm thick) of each sample were cut, deparaffinized, and rehydrated, according to standard procedures and stained with hematoxylin-eosin stain for general morphology and Von Kossa (Bio-Optica, Milan, Italy) for calcium deposition. Immunohistochemistry for the osteogenic marker Osteocalcin (OSC) (Santa Cruz Biotechnologies, USA) was also performed. For Scanning Electron Microscopy (SEM) (EVO LS-10 manufactured by ZEISS) observation, samples have been progressively dehydrated through immersion in alcohol solutions. The local changes in elemental composition were investigated using the Energy Dispersive X-ray (EDX) analyzer. Results: The results showed that BM-MSCs have higher affinity to attachment, migrate and differentiate toward the osteogenic lineage inside the novel scaffold PLA-CH both with HPL and FBS as supplement in the culture media. The use of HPL for cell expansion offers the possibility to obtain a safer cellular products without xenogenic contaminants. Cells develop a large spreading area with elongated fibroblast-like morphology preferentially inside the hydrogel pores, showing great affinity with the scaffold. This is confirmed also by histomorphological analyses at optical microscope, showing homogeneous colonization of cells inside the hydrogel pores (figure 1a). The results showed the presence of calcium deposits in the mash of the scaffold with Von Kossa stain (figure 1b), moreover cells appeared well integrated with a positivity for OSC showing a clear differentiation state as osteoblasts (figure 1c). Calcium and phosphorous were detected with SEM-EDX on the samples incubated in osteogenic medium (figure 1 d,e). Conclusion: MSCs, derived from bone marrow, associated with scaffold PLA-CH proved to be biocompatible and promising for personalized medicine. In fact, BM-MSCs were able to growth, colonize and osteo-differentiate throughout the hydrogel, demonstrating their potential application for bone regenerative medicine. Figure 1. Histomorphological analysis at the optical microscope of PLA-CH with BM-hMSCs in the GM at 100 m m ( a), Von Kossa stain showing calcium deposit distribution on PLA-CH with BM-hMSCs in the OM at 30 m m ( b), immunohistochemistry for OCN with BM-hMSCs differentiated to osteoblast in the OM at 10 m m ( c). Evaluation of calcium (Ca) and phosphorous (P) with SEM-EDX of PLA-CH with BM-hMSCs in OM day 28 ( d,e).

Guideline for design of substrate stiffness for mesenchymal stem cell culture based on heterogeneity of YAP and RUNX2 responses.

Mesenchymal stem cells (MSCs) have the potential for self-renewal and multipotency to differentiate into various lineages. Thus, they are of great interest in regenerative medicine as a cell source for tissue engineering. Substrate stiffness is one of the most extensively studied exogenous physical factors; however, consistent results have not always been reported for controlling MSCs. Conventionally used stiff culture substrates, such as tissue-culture polystyrene and glass, enhance nuclear localization of a mechanotransducer YAP and a pre-osteogenic transcription factor RUNX2, and bias MSCs towards the osteogenic lineage, even without osteogenic-inducing soluble factors. The mechanosensitive nature and intrinsic heterogeneity present challenges for obtaining reproducible results. This review summarizes the heterogeneity in human MSC response, specifically, nuclear/cytoplasmic localization changes in the mechanotransducer yes-associated protein (YAP) and the osteogenic transcription factor RUNX2, in response to substrate stiffness. In addition, a perspective on the intracellular factors attributed to response heterogeneity is discussed. The optimal range of stiffness parameters, Young's modulus, for MSC expansion culture to suppress osteogenic differentiation bias through the suppression of YAP and RUNX2 nuclear localization, and cell cycle progression is likely to be surprisingly narrow for a cell population from an identical donor and vary among cell populations from different donors. We believe that characterization of the heterogeneity of MSCs and understanding their biological meaning is an exciting research direction to establish guidelines for the design of culture substrates for the sophisticated control of MSC properties.

Periodontal ligament stem cell-based bioactive constructs for bone tissue engineering.

Objectives: Stem cell-based tissue engineering approaches are promising for bone repair and regeneration. Periodontal ligament stem cells (PDLSCs) are a promising cell source for tissue engineering, especially for maxillofacial bone and periodontal regeneration. Many studies have shown potent results via PDLSCs in bone regeneration. In this review, we describe recent cutting-edge researches on PDLSC-based bone regeneration and periodontal tissue regeneration. Data and sources: An extensive search of the literature for papers related to PDLSCs-based bioactive constructs for bone tissue engineering was made on the databases of PubMed, Medline and Google Scholar. The papers were selected by three independent calibrated reviewers. Results: Multiple types of materials and scaffolds have been combined with PDLSCs, involving xeno genic bone graft, calcium phosphate materials and polymers. These PDLSC-based constructs exhibit the potential for bone and periodontal tissue regeneration. In addition, various osteo inductive agents and strategies have been applied with PDLSCs, including drugs, biologics, gene therapy, physical stimulation, scaffold modification, cell sheets and co-culture. Conclusoin: This review article demonstrates the great potential of PDLSCs-based bioactive constructs as a promising approach for bone and periodontal tissue regeneration.

Improved contractile potential in detrusor microtissues from pediatric patients with end stage lower urinary tract dysfunction.

Autologous cell-based tissue engineering has been proposed as a treatment option for end stage lower urinary tract dysfunction (ESLUTD). However, it is generally accepted that cells isolated from patient bladders retain the pathological properties of their tissue of origin and therefore need to be improved before they can serve as a cell source for tissue engineering applications. We hypothesize that human three-dimensional (3D) microtissues of detrusor smooth muscle cells (SMCs) are valuable ex vivo disease models and potent building blocks for bladder tissue engineering. Detrusor SMCs isolated from bladder wall biopsies of pediatric ESLUTD patients and healthy controls were expanded and cultured into 3D microtissues. Gene and protein analyses were performed to explore the effect of microtissue formation on SMC viability, contractile potential, bladder wall specific extracellular matrix (ECM) composition and mediators of ECM remodeling. Through microtissue formation, remodeling and intensified cell-cell interactions, the ESLUTD SMCs lost their characteristic disease phenotype. These microtissues exhibited similar patterns of smooth muscle related contractile proteins and essential bladder wall-specific ECM components as microtissues from healthy control subjects. Thus, the presented data suggest improved contractile potential and ECM composition in detrusor SMC microtissues from pediatric ESLUTD patients. These findings are of great relevance, as 3D detrusor SMC microtissues might be an appropriate cell source for autologous cell-based bladder tissue engineering.

Advances in periodontal stem cells and the regulating niche: From in vitro to in vivo.

Periodontium possesses stem cell populations for its self-maintenance and regeneration, and has been proved to be an optimal stem cell source for tissue engineering. In vitro studies have shown that stem cells can be isolated from periodontal ligament, alveolar bone marrow and gingiva. In recent years, more studies have focused on identification of periodontal stem cells in vivo. Multiple genetic markers, including Gli1, Prx1, Axin2, αSMA, and LepR, were identified with the lineage tracing approaches. Characteristics, functions, and regulatory mechanisms of specific populations expressing one of these markers have been investigated. In vivo studies also revealed that periodontal stem cells can be regulafrted by different niche and mechanisms including intercellular interactions, ECM and multiple secreted factors. In this review, we summarized the current knowledge of in vitro characteristics and in vivo markers of periodontal stem cells, and discussed the specific regulating niche.

Stromal Vascular Fraction for Knee Osteoarthritis - An Update.

Orthobiologics never cease to cause popularity within the medical science field, distinctly in regenerative medicine. Recently, adipose tissue has been an object of interest for many researchers and medical experts due to the fact that it represents a novel and potential cell source for tissue engineering and regenerative medicine purposes. Stromal vascular fraction (SVF), for instance, which is an adipose tissue-derivative, has generated optimistic results in many scenarios. Its biological potential can be harnessed and administered into injured tissues, particularly areas in which standard healing is disrupted. This is a typical feature of osteoarthritis (OA), a common degenerative joint disease which is outlined by persistent inflammation and destruction of surrounding tissues. SVF is known to carry a large amount of stem and progenitor cells, which are able to perform self-renewal, differentiation, and proliferation. Furthermore, they also secrete several cytokines and several growth factors, effectively sustaining immune modulatory effects and halting the escalated pro-inflammatory status of OA. Although SVF has shown interesting results throughout the medical community, additional research is still highly desirable in order to further elucidate its potential regarding musculoskeletal disorders, especially OA.

Development of a Novel Perfusion Rotating Wall Vessel Bioreactor with Ultrasound Stimulation for Mass-Production of Mineralized Tissue Constructs.

As stem cells are considered a promising cell source for tissue engineering, many culture strategies have been extensively studied to generate in vitro stem cell-based tissue constructs. However, most approaches using conventional tissue culture plates are limited by the lack of biological relevance in stem cell microenvironments required for neotissue formation. In this study, a novel perfusion rotating wall vessel (RWV) bioreactor was developed for mass-production of stem cell-based 3D tissue constructs. An automated RWV bioreactor was fabricated, which is capable of controlling continuous medium perfusion, highly efficient gas exchange with surrounding air, as well as low-intensity pulsed ultrasound (LIPUS) stimulation. Embryonic stem cells encapsulated in alginate/gelatin hydrogel were cultured in the osteogenic medium by using our bioreactor system. Cellular viability, growth kinetics, and osteogenesis/mineralization were thoroughly evaluated, and culture media were profiled at real time. The in vivo efficacy was examined by a rabbit cranial defect model. Our bioreactor successfully maintained the optimal culture environments for stem cell proliferation, osteogenic differentiation, and mineralized tissue formation during the culture period. The mineralized tissue constructs produced by our bioreactor demonstrated higher void filling efficacy in the large bone defects compared to the group implanted with hydrogel beads only. In addition, the LIPUS modules mounted on our bioreactor successfully reached higher mineralization of the tissue constructs compared to the groups without LIPUS stimulation. This study suggests an effective biomanufacturing strategy for mass-production of implantable mineralized tissue constructs from stem cells that could be applicable to future clinical practice.

Histological Profiling of the Human Umbilical Cord: A Potential Alternative Cell Source in Tissue Engineering.

The embryonic development of the human umbilical cord (hUC) is complex, and different regions can be identified in this structure. The aim of this work is to characterize the hUC at in situ and ex vivo levels to stablish their potential use in vascular regeneration. Human umbilical cords were obtained and histologically prepared for in the situ analysis of four hUC regions (intervascular—IV, perivascular—PV, subaminoblastic—SAM, and Wharton’s jelly—WH), and primary cell cultures of mesenchymal stem cells (hUC-MSC) isolated from each region were obtained. The results confirmed the heterogeneity of the hUC, with the IV and PV zones tending to show the higher in situ expression of several components of the extracellular matrix (collagens, proteoglycans, and glycosaminoglycans), vimentin, and MSC markers (especially CD73), although isolation and ex vivo culture resulted in a homogeneous cell profile. Three vascular markers were positive in situ, especially vWF, followed by CD34 and CD31, and isolation and culture revealed that the region associated with the highest expression of vascular markers was IV, followed by PV. These results confirm the heterogeneity of the hUC and the need for selecting cells from specific regions of the hUC for particular applications in tissue engineering.

In vitro preparation of human Dental Pulp Stem Cell grafts with biodegradable polymer scaffolds for nerve tissue engineering.

Human Dental Pulp Stem Cells (hDPSCs) are one of the most promising stem cell sources for tissue engineering and regeneration, due to their extraordinary multi-lineage differentiation ability, ease of extraction from biological waste in dental clinics, safe non-tumorigenic phenotype, immune-tolerance upon in vivo transplantation, and great possibilities of application in autologous tissue reconstruction. The in vitro manipulation of hDPSCs paves the way for drug screening and tailor-made regeneration of damaged tissues, in the context of personalized medicine. The neural crest phenotype of these stem cells gives them the capacity to differentiate to a large variety of cell types, including neural-lineage cells. In this chapter, we describe various culture methods to generate different cellular phenotypes from hDPSCs, which can not only grow as mesenchymal-like plastic adherent cells, but also as non-adherent neurogenic dentospheres in serum-free medium. Floating dentospheres can be used to generate large populations of mature neuronal and glial marker expressing cells, which may be cultured over a substrate of nanopatterned scaffold based on biodegradable poly(lactide-co-caprolactone) (PLCL) to induce a controlled alignment of neurites and cell migration, to generate in vivo biocompatible constructs for nerve tissue bioengineering.

Differentiation Behaviour of Adipose-Derived Stromal Cells (ASCs) Seeded on Polyurethane-Fibrin Scaffolds In Vitro and In Vivo.

Adipose-derived stromal cells (ASCs) are a promising cell source for tissue engineering and regenerative medicine approaches for cartilage replacement. For chondrogenic differentiation, human (h)ASCs were seeded on three-dimensional polyurethane (PU) fibrin composites and induced with a chondrogenic differentiation medium containing TGF-ß3, BMP-6, and IGF-1 in various combinations. In addition, in vitro predifferentiated cell-seeded constructs were implanted into auricular cartilage defects of New Zealand White Rabbits for 4 and 12 weeks. Histological, immunohistochemical, and RT-PCR analyses were performed on the constructs maintained in vitro to determine extracellular matrix (ECM) deposition and expression of specific cartilage markers. Chondrogenic differentiated constructs showed a uniform distribution of cells and ECM proteins. RT-PCR showed increased gene expression of collagen II, collagen X, and aggrecan and nearly stable expression of SOX-9 and collagen I. Rabbit (r)ASC-seeded PU-fibrin composites implanted in ear cartilage defects of New Zealand White Rabbits showed deposition of ECM with structures resembling cartilage lacunae by Alcian blue staining. However, extracellular calcium deposition became detectable over the course of 12 weeks. RT-PCR showed evidence of endochondral ossification during the time course with the expression of specific marker genes (collagen X and RUNX-2). In conclusion, hASCs show chondrogenic differentiation capacity in vitro with the expression of specific marker genes and deposition of cartilage-specific ECM proteins. After implantation of predifferentiated rASC-seeded PU-fibrin scaffolds into a cartilage defect, the constructs undergo the route of endochondral ossification.

LncRNA H19 facilitates the proliferation and differentiation of human dental pulp stem cells via EZH2-dependent LATS1 methylation

Human dental pulp stem cells (hDPSCs) have been recognized as a candidate cell source for tissue engineering. Long non-coding RNAs (lncRNAs) are differentially expressed in inflamed human dental pulp tissues. The present study is aimed at investigating the role of lncRNA H19 in the differentiation potential of hDPSCs. hDPSCs were successfully isolated and cultured, followed by conducting gain and loss-of-function experiments on lncRNA H19 and large tumor suppressor 1 (LATS1) to elucidate their respective biological functions in hDPSCs. lncRNA H19 was able to promote, whereas LATS1 was found to inhibit the differentiation, proliferation, and migration capabilities of hDPSCs. LATS1 was found to activate the Hippo-Yes-associated protein (YAP) signaling pathway by decreasing levels of YAP and Tafazzin (TAZ). The effects of lncRNA H19 on hDPSCs were achieved by repressing LATS1 through enhancer of zeste homolog 2-induced trimethylation of histone 3 at lysine 27. Finally, hDPSCs overexpressing lncRNA H19 and/or LATS1 were transplanted into nude mice. It was shown that lncRNA H19 inhibited LATS1 to promote the production of odontoblasts in vivo. Taken together, lncRNA H19 serves as a contributor to the differentiation potential of hDPSCs via the inhibition of LATS1, therefore highlighting novel therapeutic targets for dental pulp repair.

Chrysin induces osteogenic differentiation of human dental pulp stem cells

ObjectivesAs an ideal cell source for tissue engineering and bone defect repair, dental pulp stem cells (DPSCs) have good osteogenic differentiation potential. Chrysin, a flavonoid extracted from oroxylum seeds, has been proven to promote bone formation of bone marrow stem cells. However, the effect of chrysin on osteogenic differentiation of DPSCs remains unclear. This study aimed to investigate the role of Chrysin in promoting osteogenic differentiation of DPSCs and in DPSC-based bone formation. Material and methodsWe investigated the effects of chrysin on DPSCs from patients by CCK-8 assay, Alizarin Red S staining, qPCR and Western blotting. The effects of chrysin on DPSC-based bone formation in a heterotopic osteogenesis model in nude mice and a rat calvarial defect model were also performed. Finally, we investigated the mechanism of chrysin-treated DPSCs by proteomics. ResultsChrysin upregulated the expression of osteogenic proteins and induced osteogenic differentiation of DPSCs. Moreover, chrysin induced abundant β-TCP-induced formation of mineralized bone tissue and promoted DPSC-based bone formation in a heterotopic osteogenesis model in nude mice and a rat calvarial defect model. Proteomics showed that upregulation of the Smad3 was closely related to osteogenic differentiation. Inhibiting of Smad3 activation by a Smad3 inhibitor could reverse the chrysin-mediated increases in the expression levels of osteogenic genes and osteogenic induction of DPSCs. ConclusionsOur study implies the intriguing potential of chrysin-treated DPSCs in bone regeneration and bone defect repair.

Pulsed Electromagnetic Field Stimulation in Osteogenesis and Chondrogenesis: Signaling Pathways and Therapeutic Implications.

Mesenchymal stem cells (MSCs) are the main cell players in tissue repair and thanks to their self-renewal and multi-lineage differentiation capabilities, they gained significant attention as cell source for tissue engineering (TE) approaches aimed at restoring bone and cartilage defects. Despite significant progress, their therapeutic application remains debated: the TE construct often fails to completely restore the biomechanical properties of the native tissue, leading to poor clinical outcomes in the long term. Pulsed electromagnetic fields (PEMFs) are currently used as a safe and non-invasive treatment to enhance bone healing and to provide joint protection. PEMFs enhance both osteogenic and chondrogenic differentiation of MSCs. Here, we provide extensive review of the signaling pathways modulated by PEMFs during MSCs osteogenic and chondrogenic differentiation. Particular attention has been given to the PEMF-mediated activation of the adenosine signaling and their regulation of the inflammatory response as key player in TE approaches. Overall, the application of PEMFs in tissue repair is foreseen: (1) in vitro: to improve the functional and mechanical properties of the engineered construct; (2) in vivo: (i) to favor graft integration, (ii) to control the local inflammatory response, and (iii) to foster tissue repair from both implanted and resident MSCs cells.

SDF Factor-1α Promotes the Migration, Proliferation, and Osteogenic Differentiation of Mouse Bone Marrow Mesenchymal Stem Cells Through the Wnt/β-Catenin Pathway.

Bone marrow mesenchymal stem cells (BMSCs) are thought to have great potential in the treatment of many diseases and may serve as a cell source for tissue engineering. These cells may be regulated by stromal cell-derived factor-1α (SDF-1α), which has been shown to promote the migration, proliferation, and osteogenic differentiation of BMSCs in inflammation-associated diseases. However, the specific mechanism underlying this process remains unclear. We herein transduced lentivirus carrying SDF-1α, empty vector, or siRNA-SDF-1α into mouse BMSCs and then performed transwell, CCK-8, cell cycle, alkaline phosphatase activity, and Alizarin Red staining experiments on the three groups of samples. Overexpression of SDF-1α promoted the migration, proliferation, and osteogenic differentiation of BMSCs, and SDF-1α upregulated the expression of Wnt pathway-related factors and downstream target genes as determined by western blot, real-time polymerase chain reaction, and immunofluorescence. The effect of low SDF-1α expression on BMSCs was significantly weakened. In addition, we transduced lentivirus carrying siRNA-Wnt3a into BMSCs and treated them with SDF-1 drugs. After inhibiting the Wnt pathway, SDF-1 significantly weakened the migration, proliferation, and osteogenic differentiation of BMSCs. From this, we concluded that high SDF-1 expression can promote the migration, proliferation, and osteogenic differentiation of BMSCs, at least in part by activating the Wnt pathway.

Guiding Lineage Specific Differentiation of SHED for Target Tissue/Organ Regeneration.

Stem cells from Human Exfoliated Deciduous teeth (SHED) are considered one of the most attractive cell sources for tissue engineering due to their easy acquisition with no donor morbidity, ready availability, ability to self-renew with high proliferation, capacity for multilineage differentiation and immunomodulatory functions. To date, SHED are able to differentiate into odonto-/ osteoblasts, neuronal cells, endothelial cells, hepatocyte-like cells, chondrocytes, epidermal cells among many other cell types. Accordingly, SHED possess a promising potential to be used in the cell-based therapy for various diseases, including reversible pulpitis, orofacial bone defects, neurodevelopmental disease and ischemic injury. Despite this potential, it has been a concern that tissue specific stem cells do not differentiate with the same efficacy into all the different lineages as they may have an inherent tendency to differentiate toward the tissues from which they were originally derived. Furthermore, stem cell niche comprises of a complex microenvironment where various cells, soluble signals, extracellular matrix and physical cues interplay to maintain the stemness of SHED and modulate their differentiation. Therefore, it is of significant importance to identify the specific microenvironmental cues that regulate lineage specific differentiation of SHED, which could inspire to develop functional approaches in target tissue regeneration. In this review, we highlight the recent studies that demonstrated multilineage differentiation capacity of SHED, focusing on how the microenvironment could be modified using different cues in order to achieve tissue specific regeneration.

Dental stem cells: The role of biomaterials and scaffolds in developing novel therapeutic strategies

Dental stem cells (DSCs) are self-renewable cells that can be obtained easily from dental tissues, and are a desirable source of autologous stem cells. The use of DSCs for stem cell transplantation therapeutic approaches is attractive due to their simple isolation, high plasticity, immunomodulatory properties, and multipotential abilities. Using appropriate scaffolds loaded with favorable biomolecules, such as growth factors, and cytokines, can improve the proliferation, differentiation, migration, and functional capacity of DSCs and can optimize the cellular morphology to build tissue constructs for specific purposes. An enormous variety of scaffolds have been used for tissue engineering with DSCs. Of these, the scaffolds that particularly mimic tissue-specific micromilieu and loaded with biomolecules favorably regulate angiogenesis, cell-matrix interactions, degradation of extracellular matrix, organized matrix formation, and the mineralization abilities of DSCs in both in vitro and in vivo conditions. DSCs represent a promising cell source for tissue engineering, especially for tooth, bone, and neural tissue restoration. The purpose of the present review is to summarize the current developments in the major scaffolding approaches as crucial guidelines for tissue engineering using DSCs and compare their effects in tissue and organ regeneration.