Biosynthesis of collagen I, II, RUNX2 and lubricin at different time points of chondrogenic differentiation in a 3D in vitro model of human mesenchymal stem cells derived from adipose tissue

Adipose-Derived Mesenchymal Stromal Cells: A Tool for Bone and Cartilage Repair

The osteogenic and chondrogenic differentiation ability of adipose-derived mesenchymal stromal cells (ASCs) and their potential therapeutic applications in bone and cartilage defects are reported in this review. This becomes particularly important when these disorders can only be poorly treated by conventional therapeutic approaches, and tissue engineering may represent a valuable alternative. Being of mesodermal origin, ASCs can be easily induced to differentiate into chondrocyte-like and osteocyte-like elements and used to repair damaged tissues. Moreover, they can be easily harvested and used for autologous implantation. A plethora of ASC-based strategies are being developed worldwide: they include the transplantation of freshly harvested cells, in vitro expanded cells or predifferentiated cells. Moreover, improving their positive effects, ASCs can be implanted in combination with several types of scaffolds that ensure the correct cell positioning; support cell viability, proliferation and migration; and may contribute to their osteogenic or chondrogenic differentiation. Examples of these strategies are described here, showing the enormous therapeutic potential of ASCs in this field. For safety and regulatory issues, most investigations are still at the experimental stage and carried out in vitro and in animal models. Clinical applications have, however, been reported with promising results and no serious adverse effects.

Mesenchymal stromal cells in tumor microenvironment remodeling of BCR-ABL negative myeloproliferative diseases

Chronic myeloproliferative neoplasms encompass the BCR-ABL1-negative neoplasms polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). These are characterized by calreticulin (CALR), myeloproliferative leukemia virus proto-oncogene (MPL) and the tyrosine kinase Janus kinase 2 (JAK2) mutations, eventually establishing a hyperinflammatory tumor microenvironment (TME). Several reports have come to describe how constitutive activation of JAK-STAT and NFκB signaling pathways lead to uncontrolled myeloproliferation and pro-inflammatory cytokines secretion. In such a highly oxidative TME, the balance between Hematopoietic Stem Cells (HSCs) and Mesenchymal Stromal Cells (MSCs) has a crucial role in MPN development. For this reason, we sought to review the current literature concerning the interplay between HSCs and MSCs. The latter have been reported to play an outstanding role in establishing of the typical bone marrow (BM) fibrotic TME as a consequence of the upregulation of different fibrosis-associated genes including PDGF- β upon their exposure to the hyperoxidative TME characterizing MPNs. Therefore, MSCs might turn to be valuable candidates for niche-targeted targeting the synthesis of cytokines and oxidative stress in association with drugs eradicating the hematopoietic clone.

Neurotrophic and immunomodulatory effects of olfactory ensheathing cells as a strategy for neuroprotection and regeneration

Accumulating evidence sustains glial cells as critical players during central nervous system (CNS) development, homeostasis and disease. Olfactory ensheathing cells (OECs), a type of specialized glia cells sharing properties with both Schwann cells and astrocytes, are of critical importance in physiological condition during olfactory system development, supporting its regenerative potential throughout the adult life. These characteristics prompted research in the field of cell-based therapy to test OEC grafts in damaged CNS. Neuroprotective mechanisms exerted by OEC grafts are not limited to axonal regeneration and cell differentiation. Indeed, OEC immunomodulatory properties and their phagocytic potential encourage OEC-based approaches for tissue regeneration in case of CNS injury. Herein we reviewed recent advances on the immune role of OECs, their ability to modulate CNS microenvironment via bystander effects and the potential of OECs as a cell-based strategy for tissue regeneration.

Restoring Osteochondral Defects through the Differentiation Potential of Cartilage Stem/Progenitor Cells Cultivated on Porous Scaffolds

Cartilage stem/progenitor cells (CSPCs) are cartilage-specific, multipotent progenitor cells residing in articular cartilage. In this study, we investigated the characteristics and potential of human CSPCs combined with poly(lactic-co-glycolic acid) (PLGA) scaffolds to induce osteochondral regeneration in rabbit knees. We isolated CSPCs from human adult articular cartilage undergoing total knee replacement (TKR) surgery. We characterized CSPCs and compared them with infrapatellar fat pad-derived stem cells (IFPs) in a colony formation assay and by multilineage differentiation analysis in vitro. We further evaluated the osteochondral regeneration of the CSPC-loaded PLGA scaffold during osteochondral defect repair in rabbits. The characteristics of CSPCs were similar to those of mesenchymal stem cells (MSCs) and exhibited chondrogenic and osteogenic phenotypes without chemical induction. For in vivo analysis, CSPC-loaded PLGA scaffolds produced a hyaline-like cartilaginous tissue, which showed good integration with the host tissue and subchondral bone. Furthermore, CSPCs migrated in response to injury to promote subchondral bone regeneration. Overall, we demonstrated that CSPCs can promote osteochondral regeneration. A monophasic approach of using diseased CSPCs combined with a PLGA scaffold may be beneficial for repairing complex tissues, such as osteochondral tissue.

Sequential growth factor exposure of human Ad-MSCs improves chondrogenic differentiation in an osteochondral biphasic implant

Joint cartilage damage affects 10-12% of the world's population. Medical treatments improve the short-term quality of life of affected individuals but lack a long-term effect due to injury progression into fibrocartilage. The use of mesenchymal stem cells (MSCs) is one of the most promising strategies for tissue regeneration due to their ability to be isolated, expanded and differentiated into metabolically active chondrocytes to achieve long-term restoration. For this purpose, human adipose-derived MSCs (Ad-MSCs) were isolated from lipectomy and grown in xeno-free conditions. To establish the best differentiation potential towards a stable chondrocyte phenotype, isolated Ad-MSCs were sequentially exposed to five differentiation schemes of growth factors in previously designed three-dimensional biphasic scaffolds with incorporation of a decellularized cartilage matrix as a bioactive ingredient, silk fibroin and bone matrix, to generate a system capable of being loaded with pre-differentiated Ad-MSCs, to be used as a clinical implant in cartilage lesions for tissue regeneration. Chondrogenic and osteogenic markers were analyzed by reverse transcription-quantitative PCR and cartilage matrix generation by histology techniques at different time points over 40 days. All groups had an increased expression of chondrogenic markers; however, the use of fibroblast growth factor 2 (10 ng/ml) followed by a combination of insulin-like growth factor 1 (100 ng/ml)/TGFβ1 (10 ng/ml) and a final step of exposure to TGFβ1 alone (10 ng/ml) resulted in the most optimal chondrogenic signature towards chondrocyte differentiation and the lowest levels of osteogenic expression, while maintaining stable collagen matrix deposition until day 33. This encourages their possible use in osteochondral lesions, with appropriate properties for use in clinical patients.

Cell Sources for Human In vitro Bone Models

PURPOSE OF REVIEW

One aim in bone tissue engineering is to develop human cell-based, 3D in vitro bone models to study bone physiology and pathology. Due to the heterogeneity of cells among patients, patient's own cells are needed to be obtained, ideally, from one single cell source. This review attempts to identify the appropriate cell sources for development of such models.

RECENT FINDINGS

Bone marrow and peripheral blood are considered as suitable sources for extraction of osteoblast/osteocyte and osteoclast progenitor cells. Recent studies on these cell sources have shown no significant differences between isolated progenitor cells. However, various parameters such as medium composition affect the cell's proliferation and differentiation potential which could make the peripheral blood-derived stem cells superior to the ones from bone marrow. Peripheral blood can be considered a suitable source for osteoblast/osteocyte and osteoclast progenitor cells, being less invasive for the patient. However, more investigations are needed focusing on extraction and differentiation of both cell types from the same donor sample of peripheral blood.

Co-culture and Mechanical Stimulation on Mesenchymal Stem Cells and Chondrocytes for Cartilage Tissue Engineering

Defects in articular cartilage injury and chronic osteoarthritis are very widespread and common, and the ability of injured cartilage to repair itself is limited. Stem cell-based cartilage tissue engineering provides a promising therapeutic option for articular cartilage damage. However, the application of the technique is limited by the number, source, proliferation, and differentiation of stem cells. The co-culture of mesenchymal stem cells and chondrocytes is available for cartilage tissue engineering, and mechanical stimulation is an important factor that should not be ignored. A combination of these two approaches, i.e., co-culture of mesenchymal stem cells and chondrocytes under mechanical stimulation, can provide sufficient quantity and quality of cells for cartilage tissue engineering, and when combined with scaffold materials and cytokines, this approach ultimately achieves the purpose of cartilage repair and reconstruction. In this review, we focus on the effects of co-culture and mechanical stimulation on mesenchymal stem cells and chondrocytes for articular cartilage tissue engineering. An in-depth understanding of the impact of co-culture and mechanical stimulation of mesenchymal stem cells and chondrocytes can facilitate the development of additional strategies for articular cartilage tissue engineering.

Mesenchymal stem cells regulate inflammatory milieu within degenerative nucleus pulposus cells via p38 MAPK pathway

It has been established that excessive apoptosis of nucleus pulposus cells (NPCs) are responsible for pathogenesis of human intervertebral disc degeneration (IDD). The present study aimed to shed light on the molecular mechanisms underlying the protective effects of mesenchymal stem cells (MSCs) on NPCs in an inflammatory environment. NPCs were treated with TNF-α to induce inflammation and then co-cultured with Wharton's Jelly-derived MSCs (WJ-MSCs)without direct interaction. The levels of inflammation markers (IL-1β, IL-6 and IL-8) in NPCs were detected by performing enzyme-linked immunosorbent assay (ELISA), and expression of metalloproteases and aggrecan, as well as the activity of p38 MAPK pathway were determined through immunoblotting. SB-203580 was used to inhibit p38 signaling, prior to evaluation of the effects of Wharton's Jelly-derived MSCs (WJ-MSCs) on inflammatory response within the co-cultured NPCs. After TNF-α treatment, the levels of inflammatory cytokines, MMP-3, and MMP-13 in NPCs were increased whereas aggrecan was decreased, which was then dramatically reversed by WJ-MSCs co-culture. Likewise, WJ-MSCs suppressed TNF-α-induced phosphorylation of p38 MAPK signaling components including p38, ASK-1, MKK-3 and MKK-6. Blocking p38 MAPK pathway enhanced the anti-inflammatory impact of WJ-MSCs, and there was no significant difference between NPCs co-cultured with WJ-MSCs or the cells cultured alone. WJ-MSCs co-culture mitigate TNF-α-induced inflammatory response and ECM degeneration in NPCs, the major pathological events are implicated in IDD development, probably by suppressing the p38 MAPK signaling cascade.

Primary chondrocyte exosomes mediate osteoarthritis progression by regulating mitochondrion and immune reactivity

Aim: We aimed to investigate the proteomics of primary chondrocyte exosomes and the effect of exosomes in osteoarthritis (OA) treatment. Materials & methods: We isolated exosomes from primary chondrocytes cultured in normal (D0) and inflammatory environments induced by IL-1β and determined the proteomics of these exosomes. Next, we investigated what effect and mechanism D0 chondrocytes exosomes have in OA treatment. Results: There were more proteins that belonged to mitochondrion and were involved in immune system processes in D0 exosomes. Notably, intra-articular administration of D0 exosomes successfully prevented the development of OA. D0 chondrocyte exosomes could restore mitochondrial dysfunction and polarize macrophage response toward an M2 phenotype. Conclusion: Our findings demonstrated that primary chondrocyte exosomes are efficient in OA treatment.

Decellularized adipose matrix provides an inductive microenvironment for stem cells in tissue regeneration

Stem cells play a key role in tissue regeneration due to their self-renewal and multidirectional differentiation, which are continuously regulated by signals from the extracellular matrix (ECM) microenvironment. Therefore, the unique biological and physical characteristics of the ECM are important determinants of stem cell behavior. Although the acellular ECM of specific tissues and organs (such as the skin, heart, cartilage, and lung) can mimic the natural microenvironment required for stem cell differentiation, the lack of donor sources restricts their development. With the rapid development of adipose tissue engineering, decellularized adipose matrix (DAM) has attracted much attention due to its wide range of sources and good regeneration capacity. Protocols for DAM preparation involve various physical, chemical, and biological methods. Different combinations of these methods may have different impacts on the structure and composition of DAM, which in turn interfere with the growth and differentiation of stem cells. This is a narrative review about DAM. We summarize the methods for decellularizing and sterilizing adipose tissue, and the impact of these methods on the biological and physical properties of DAM. In addition, we also analyze the application of different forms of DAM with or without stem cells in tissue regeneration (such as adipose tissue), repair (such as wounds, cartilage, bone, and nerves), in vitro bionic systems, clinical trials, and other disease research.

miR‑10a‑5p inhibits osteogenic differentiation of bone marrow‑derived mesenchymal stem cells

The use of human bone marrow mesenchymal stem cells (hBMSCs) as a tissue engineering application for individuals affected by osteoporosis and other types of bone loss diseases has been well studied in recent years. The osteogenic differentiation of hBMSCs can be regulated by a number of cues. MicroRNAs (miRNAs/miRs) serve as the key regulators of various biological processes; however, to the best of our knowledge, no information exists with regards to the specific modulatory effects of miR-10a-5p on osteogenic differentiation of hBMSCs. The aim of the present study was to investigate the relationship between hBMSCs and miR-10a-5p and, ultimately, to determine how miR-10a-5p affects the osteogenic differentiation process of hBMSCs in vitro and in vivo. The hBMSCs used in the present study were transfected with mirVana™ miRNA inhibitors and mimics, and transfection efficiency was assessed by fluorescence microscopy and reverse transcription-quantitative PCR (RT-qPCR). Viability of hBMSCs following transfection was analyzed using a Cell Counting Kit-8 assay. The mRNA expression levels of specific osteoblast markers, including alkaline phosphatase (ALP) and runt-related transcription factor 2 (RUNX2) were measured using RT-qPCR and western blot analysis. New bone formation was evaluated by Goldner's trichrome staining and micro-CT analysis in vivo. No significant difference in cell viability was observed among the different groups 24 h post-transfection. Overexpression of miR-10a-5p inhibited the expression of osteoblast makers in hBMSCs, whereas inhibition of miR-10a-5p upregulated the expression of ALP and RUNX2 in vitro. Furthermore, miR-10a-5p acted as a suppressor during the process of new bone formation in vivo. In conclusion, the findings of the present study suggested that miR-10a-5p served as a negative regulatory factor during osteoblast differentiation of hBMSCs and may be utilized in a treatment approach for bone repair in osteogenic-related diseases.

Cycloastragenol as an Exogenous Enhancer of Chondrogenic Differentiation of Human Adipose-Derived Mesenchymal Stem Cells. A Morphological Study

Stem cell therapy and tissue engineering represent a promising approach for cartilage regeneration. However, they present limits in terms of mechanical properties and premature de-differentiation of engineered cartilage. Cycloastragenol (CAG), a triterpenoid saponin compound and a hydrolysis product of the main ingredient in Astragalus membranaceous, has been explored for cartilage regeneration. The aim of this study was to investigate CAG’s ability to promote cell proliferation, maintain cells in their stable active phenotype, and support the production of cartilaginous extracellular matrix (ECM) in human adipose-derived mesenchymal stem cells (hAMSCs) in up to 28 days of three-dimensional (3D) chondrogenic culture. The hAMSC pellets were cultured in chondrogenic medium (CM) and in CM supplemented with CAG (CAG–CM) for 7, 14, 21, and 28 days. At each time-point, the pellets were harvested for histological (hematoxylin and eosin (H&E)), histochemical (Alcian-Blue) and immunohistochemical analysis (Type I, II, and X collagen, aggrecan, SOX9, lubricin). After excluding CAG’s cytotoxicity (MTT Assay), improved cell condensation, higher glycosaminoglycans (sGAG) content, and increased cell proliferation have been detected in CAG–CM pellets until 28 days of culture. Overall, CAG improved the chondrogenic differentiation of hAMSCs, maintaining stable the active chondrocyte phenotype in up to 28 days of 3D in vitro chondrogenic culture. It is proposed that CAG might have a beneficial impact on cartilage regeneration approaches.

Adipose stromal/stem cells in regenerative medicine: Potentials and limitations

This article presents the stem and progenitor cells from subcutaneous adipose tissue, briefly comparing them with their bone marrow counterparts, and discussing their potential for use in regenerative medicine. Subcutaneous adipose tissue differs from other mesenchymal stromal/stem cells (MSCs) sources in that it contains a pre-adipocyte population that dwells in the adventitia of robust blood vessels. Pre-adipocytes are present both in the stromal-vascular fraction (SVF; freshly isolated cells) and in the adherent fraction of adipose stromal/stem cells (ASCs; in vitro expanded cells), and have an active role on the chronic inflammation environment established in obesity, likely due their monocytic-macrophage lineage identity. The SVF and ASCs have been explored in cell therapy protocols with relative success, given their paracrine and immunomodulatory effects. Importantly, the widely explored multipotentiality of ASCs has direct application in bone, cartilage and adipose tissue engineering. The aim of this editorial is to reinforce the peculiarities of the stem and progenitor cells from subcutaneous adipose tissue, revealing the spheroids as a recently described biotechnological tool for cell therapy and tissue engineering. Innovative cell culture techniques, in particular 3D scaffold-free cultures such as spheroids, are now available to increase the potential for regeneration and differentiation of mesenchymal lineages. Spheroids are being explored not only as a model for cell differentiation, but also as powerful 3D cell culture tools to maintain the stemness and expand the regenerative and differentiation capacities of mesenchymal cell lineages.

Mechanical stimulation promotes the proliferation and the cartilage phenotype of mesenchymal stem cells and chondrocytes co-cultured in vitro

Mesenchymal stem cells and chondrocytes are an important source of the cells for cartilage tissue engineering. Therefore, the culture and expansion methods of these cells need to be improved to overcome the aging of chondrocytes and induced chondrogenic differentiation of mesenchymal stem cells. The aim of this study was to expand the cells for cartilage tissue engineering by combining the advantages of growing cells in co-culture and under a mechanically-stimulated environment. Rabbit chondrocytes and co-cultured cells (bone mesenchymal stem cells and chondrocytes) were subjected to cyclic sinusoidal dynamic tensile mechanical stimulationusing the FX-4000 tension system. Chondrocyte proliferation was assayed by flow cytometry and CFSE labeling. The cell cartilage phenotype was determined by detecting GAG, collagen II and TGF-β1 protein expression by ELISA and the Col2α1, TGF-β1 and Sox9 gene expression by RT-PCR. The results show that the co-culture improved both the proliferation ability of chondrocytes and the cartilage phenotype of co-cultured cells. A proper cyclic sinusoidal dynamic tensile mechanical stimulation improved the proliferation ability and cartilage phenotype of chondrocytes and co-cultured cells. These results suggest that the co-culture of mesenchymal stem cells with chondrocytes and proper mechanical stimulation may be an appropriate way to rapidly expand the cells that have an improved cartilage phenotype for cartilage tissue engineering.

Significantly dysregulated genes in osteoarthritic labrum cells identified through gene expression profiling

The aim of the present study was to explore the molecular basis and identify significant genetic alterations in acetabular labrum cells associated with osteoarthritis (OA). Gene expression data of osteoarthritic and normal human labrum cells were downloaded from a public database and reanalyzed. Significant differentially expressed genes (DEGs) were acquired by performing a thorough analysis of microarray data between the OA acetabular labrum cells and control cells. Key genes in OA labrum cells were revealed by a combination of weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) analysis. Literature mining and drug screening were further performed for these key genes. In total, 141 DEGs between OA and normal labrum cells were identified. In addition, WGCNA and PPI analysis identified 23 DEGs as key genes in the OA labrum. All the key genes were significantly downregulated in OA labrum cells and were grouped into two different WGCNA-PPI common subnetworks. Kinase insert domain receptor (KDR), CD34, cadherin 5 (CDH5), Fms related tyrosine kinase 1 (FLT1) and asporin were hub nodes in the PPI network of DEGs. These key genes were significantly enriched in functional clusters of transforming growth factor, alkaline phosphatase, bone morphogenic protein and extracellular matrix. Drug screening analysis identified several drugs targeting the key genes, including arachidonic acid, yohimbic acid and mimosine. The results of the present study indicate that the changes of FLT1, KDR, CD34 and CDH5 in acetabular labrum cells may be involved in the pathogenesis of OA and could serve as biomarkers and therapeutic targets of OA. Additionally, arachidonic acid, yohimbic acid and mimosine may act as potential drugs for OA.

Functional Biomolecule Delivery Systems and Bioengineering in Cartilage Regeneration

Osteoarthritis (OA) is a common degenerative disease which involves articular cartilage, and leads to total joint disability in the advanced stages. Due to its avascular and aneural nature, damaged cartilage cannot regenerate itself. Stem cell therapy and tissue engineering represent a promising route in OA therapy, in which cooperation of mesenchymal stem cells (MSCs) and three-dimensional (3D) scaffolds contribute to cartilage regeneration. However, this approach still presents some limits such as poor mechanical properties of the engineered cartilage. The natural dynamic environment of the tissue repair process involves a collaboration of several signals expressed in the biological system in response to injury. For this reason, tissue engineering involving exogenous "influencers" such as mechanostimulation and functional biomolecule delivery systems (BDS), represent a promising innovative approach to improve the regeneration process. BDS provide a controlled release of biomolecules able to interact between them and with the injured tissue. Nano-dimensional BDS is the future hope for the design of personalized scaffolds, able to overcome the delivery problems. MSC-derived extracellular vesicles (EVs) represent an attractive alternative to BDS, due to their innate targeting abilities, immunomodulatory potential and biocompatibility. Future advances in cartilage regeneration should focus on multidisciplinary strategies such as modular assembly strategies, EVs, nanotechnology, 3D biomaterials, BDS, mechanobiology aimed at constructing the functional scaffolds for actively targeted biomolecule delivery. The aim of this review is to run through the different approaches adopted for cartilage regeneration, with a special focus on biomaterials, BDS and EVs explored in terms of their delivery potential, healing capabilities and mechanical features.

Decreased synovial fluid pituitary adenylate cyclase-activating polypeptide (PACAP) levels may reflect disease severity in post-traumatic knee osteoarthritis after anterior cruciate ligament injury

BACKGROUND

It has been demonstrated that anterior cruciate ligament (ACL) injury-induced cartilage degeneration is the key risk factor for post-traumatic knee osteoarthritis (PTKOA).Pituitary adenylate cyclase-activating polypeptide (PACAP), a common neuropeptide exerting a wide spectrum of functions, has been proved to inhibit inflammation and prevent cartilage degeneration.

OBJECTIVE

The current study was performed to investigate circulating and synovial fluid PACAP concentrations in ACL injury patients to determine their relationship with the disease progression of the severity of post-traumatic knee osteoarthritis (PTKOA).

METHODS

72 ACL injury patients receiving arthroscopical examination and surgery were enrolled in the study. Meanwhile, 60 gender-and-age non-traumatic patellar dislocation patients were enrolled as controls. The VAS score, Lysholm Score and International Knee Documentation Committee (IKDC) score were all recorded to evaluate the clinical severity. Serum and synovial fluid (SF) PACAP levels were investigated by enzyme-linked immunosorbent assay (ELISA).The IL-1β and TNF-α levels were also investigated. The degree of meniscus injury was assessed by MR imaging. The modified Mankin score was recorded to examine the cartilage histopathological alternations. Receiver operating characteristic (ROC) curve was performed to discuss the diagnostic value of PACAP levels for the prediction of the radiographic grading in comparison with IL-1β and TNF-α.

RESULTS

Serum PACAP levels between PTKOA patients and patellar dislocation did not reach significant differences. However, SF PACAP levels were significantly lower in PTKOA patients than controls. In addition, SF PACAP levels were negatively associated with MRI imaging grade for meniscus injury and VAS score, and were positively associated with Lysholm and IKDC scores. In addition, SF PACAP levels were negatively related to Mankin score as well as the expressions of IL-1β and TNF-α. ROC analysis curve showed that attenuated PACAP may serve as a favorable marker for the diagnosis of MRI for meniscus injury.

CONCLUSIONS

SF PACAP concentrations showed an independent and negative association with disease severity in PTKOA following ACL injury. Local treatment with PACAP may act as a possible adjuvant therapy for delaying the process of PTKOA.

Adapted Moderate Training Exercise Decreases the Expression of Ngal in the Rat Kidney: An Immunohistochemical Study

Neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of several injuries and is upregulated in inflammatory conditions. Vitamin D was shown to have anti-inflammatory effects and to increase after physical activity. This work aimed to assess, through immunohistochemistry, the effects of an adapted moderate training exercise (AMTE) on the expression of NGAL and vitamin D receptor (VDR) in the kidney and heart of rats. Sixteen rats were distributed into two groups: the sedentary control group and the experimental group, subjected to AMTE on the treadmill for 12 weeks. The results showed the basal expression of NGAL and VDR in both the heart and the kidney in sedentary rats; no differences in the expression of both NGAL and VDR in the heart; and a decreased NGAL and an increased VDR expression in the kidney of rats subjected to AMTE. These results suggest a possible protective role of AMTE on NGAL-associated injuries in the kidney, probably through the vitamin D signaling pathway. Our results represent an interesting preliminary data that may open new horizons in the management of NGAL-associated kidney injuries. However, further studies are needed to confirm these results and to comprehend the specific interaction between NGAL and VDR pathways in the kidney.

Effect of autologous adipose-derived mesenchymal stem cell therapy in the treatment of acromioclavicular joint osteoarthritis

The aim of this case report is to evaluate the efficacy of mesenchymal stem cell (MSC) therapy in the treatment of small joint osteoarthritis (OA). Acromio-clavicular (AC) joint OA is an under-diagnosed and yet frequent source of shoulder pain. MSCs have shown evidence of benefit in the treatment of knee OA. This is the first report to describe the use of MSC therapy in OA of the upper limb. A 43-year-old patient presents with painful AC joint OA and undergoes MSC therapy. The patient reported pain and functional improvement as assessed by the Disability of Arm, Shoulder and Hand Score and Numeric Pain Rating Scale. Imaging at 12 months showed structural improvement with reduction in subchondral oedema, synovitis and subchondral cysts. This case is the first to show the benefit of MSC therapy in the treatment of small joint arthropathy and also of the upper limb.

Trial registration number: Australian New Zealand Clinical Trials Registry (ACTRN12617000638336).

Adipose derived mesenchymal stem cells alleviated osteoarthritis and chondrocyte apoptosis through autophagy inducing

OBJECTIVE

We aim to explore the effect of adipose derived mesenchymal stem cells (ADMSCs) on a knee osteoarthritis rat model and analyze how ADMSCs affect chondrocyte apoptosis.

MATERIALS AND METHODS

A surgically induced rat knee osteoarthritis (OA) model was constructed. ADMSCs were engrafted into the right knee cavity. Hematoxylin and eosin (H&E), Masson, and Safranin O were used to compare the histopathology of synovial membrane and cartilage. Immunohistochemical (IHC) was used to measure MMP-13, Collagen 2 (Col-2), Caspase-3 (Cas-3), PARP, p62, LC3b, DDR-2, FGFR-1, Wnt, P-AKT/AKT, p-CAMKII/CAMKII, and p-Smad1/Smad1 expression in the articular cartilage. qPCR and Western blot analysis were used to detect mRNA and protein levels of markers in chondrocytes. TUNEL and Annexin-V were used to assess apoptosis.

RESULTS

Histological analysis showed that ADMSCs alleviated the deterioration of cartilage and osteoarthritis. ADMSCs coculture increase the expression of Col2 and Sox-9, while down regulated MMP-13 in IL-1β stimulated chondrocytes. ADMSCs decreased proinflammatory cytokines IL-1β, IL-6, and TNF-α. ADMSCs enhanced the viability of IL-1β stimulated chondrocytes. ADMSC attenuated chondrocyte apoptosis. The pretreatment of 3-methyladenine (3-MA) reversed the reduction of Caspase-3 caused by ADMSCs, showing that the antiapoptotic effect was associated with autophagy inducing. ADMSCs significantly reduced the expression of FGFR-1, DDR-2, and Wnt in IL-1β stimulated chondrocytes. ADMSCs reduced the ratio of p-Smad1/Smad1 and p-CAMK II/CAMKII, and increased the ratio of p-AKT/AKT.

CONCLUSIONS

ADMSCs treatment alleviate osteoarthritis in rat OA models. AMDSCs reduced the secretion of proinflammatory cytokines and protected against apoptosis through autophagy inducing. ADMSCs' function could be related to multiple signaling pathway.

Impact of Mechanical Load on the Expression Profile of Synovial Fibroblasts from Patients with and without Osteoarthritis

Osteoarthritis (OA) affects the integrity of the entire joint including the synovium. The most abundant cells in the synovium are fibroblasts (SF). Excessive mechanical loading might contribute to OA pathogenesis. Here, we investigate the effects of mechanical loading on SF derived from non-OA (N-SF) and OA patients (OA-SF). We treated N-SF and OA-SF with or without mechanical loading for 48h after 24h of preincubation. Then we assessed gene and protein expression of proinflammatory factors (TNFα, COX-2, PG-E2, IL-6), extracellular matrix (ECM) components (COL1, FN1) and glycosaminoglycans (GAGs) via RT-qPCR, ELISA, DMMB assay and HPLC. Mechanical loading significantly increased TNFα and PG-E2 secretion by N-SF and OA-SF, whereas in OA-SF IL-6 secretion was reduced. COL1 and FN1 secretion were downregulated in N-SF during loading. OA-SF secreted less COL1 compared to N-SF under control conditions. In contrast, OA-SF in general expressed more FN1. GAG synthesis was upregulated in N-SF, but not in OA-SF during loading with OA-SF displaying a higher charge density than N-SF. Mechanical loading enhanced proinflammatory factor expression and GAG synthesis and decreased secretion of ECM components in N-SFs, indicating a contributing role of SF to OA development.

An updated review of adipose derived-mesenchymal stem cells and their applications in musculoskeletal disorders

INTRODUCTION

Adipose-derived mesenchymal stem cells (ASCs) represent a new therapeutic strategy in biomedicine with many potential applications, especially in musculoskeletal disorders. Preclinical and clinical studies based on the administration of ASCs support their efficacy in bone regeneration, joint repair, tendon injury and skeletal muscle alterations. Many of these novel treatments may improve patients' quality of life and prognosis. However, several concerns about the use of stem cells remain unsolved, particularly regarding their safety and side effects. The present work aims to review the nature, clinical trials and patents involving the use of ASCs in musculoskeletal disorders.

AREAS COVERED

In this article, we describe ASCs' isolation, culture and differentiation in vivo and in vitro, advances on ASCs' applications in bone, cartilage, muscle and tendon repair, and patents involving the use of ASCs.

EXPERT OPINION

The use of ASCs in musculoskeletal disorders presents significant therapeutic advantages, including limited autoimmune response, potential cell expansion ex vivo, high plasticity to differentiate into several mesodermal cell lineages, and additional effects of therapeutic interest such as secretion of neurotrophic factors and anti-inflammatory properties. For these reasons, ASCs are promising therapeutic agents for clinical applications in musculoskeletal disorders.

Moderate Physical Activity as a Prevention Method for Knee Osteoarthritis and the Role of Synoviocytes as Biological Key

The purpose of this study was to investigate the influence of moderate physical activity (MPA) on the expression of osteoarthritis (OA)-related (IL-1β, IL-6, TNF-α, MMP-13) and anti-inflammatory and chondroprotective (IL-4, IL-10, lubricin) biomarkers in the synovium of an OA-induced rat model. A total of 32 rats were divided into four groups: Control rats (Group 1); rats performing MPA (Group 2); anterior cruciate ligament transection (ACLT)-rats with OA (Group 3); and, ACLT-rats performing MPA (Group 4). Analyses were performed using Hematoxylin & Eosin (H&E) staining, histomorphometry and immunohistochemistry. In Group 3, OA biomarkers were significantly increased, whereas, IL-4, IL-10, and lubricin were significantly lower than in the other experimental groups. We hypothesize that MPA might partake in rescuing type B synoviocyte dysfunction at the early stages of OA, delaying the progression of the disease.

The Synovium Theory: Can Exercise Prevent Knee Osteoarthritis? The Role of "Mechanokines", A Possible Biological Key

Osteoarthritis (OA) is a debilitating disease widespread in the world, having a negative impact on daily activities, especially in old age [...].

The "Journal of Functional Morphology and Kinesiology" Journal Club Series: Highlights on Recent Papers in Exercise and Osteoarthritis

We are glad to introduce the eleventh Journal Club. This edition is focused on several relevant studies published in the last years in the field of exercise and osteoarthritis, chosen by our Editorial Board members and their colleagues. We hope to stimulate your curiosity in this field and to share with you the passion for sport seen also from the scientific point of view. The Editorial Board members wish you an inspiring lecture.

A correlation between intestinal microbiota dysbiosis and osteoarthritis

Osteoarthritis (OA) is a degenerative disease of the articular cartilage, resulting in pain and total joint disability. Recent studies focused on the role of the metabolic syndrome in inducing or worsening joint damage suggest that chronic low-grade systemic inflammation may represent a possible linking factor. This finding supports the concept of a new phenotype of OA, a metabolic OA. The gut microbiome is fundamental for human physiology and immune system development, among the other important functions. Manipulation of the gut microbiome is considered an important topic for the individual health in different medical fields such as medical biology, nutrition, sports, preventive and rehabilitative medicine. Since intestinal microbiota dysbiosis is strongly associated with the pathogenesis of several metabolic and inflammatory diseases, it is conceivable that also the pathogenesis of OA might be related to it. However, the mechanisms and the contribution of intestinal microbiota metabolites in OA pathogenesis are still not clear. The aim of this narrative review is to review recent literature concerning the possible contribution of dysbiosis to OA onset and to discuss the importance of gut microbiome homeostasis maintenance for optimal general health preservation.

Continuous Passive Motion Promotes and Maintains Chondrogenesis in Autologous Endothelial Progenitor Cell-Loaded Porous PLGA Scaffolds during Osteochondral Defect Repair in a Rabbit Model

Continuous passive motion (CPM) is widely used after total knee replacement. In this study, we investigated the effect of CPM combined with cell-based construct-transplantation in osteochondral tissue engineering. We created osteochondral defects (3 mm in diameter and 3 mm in depth) in the medial femoral condyle of 36 knees and randomized them into three groups: ED (empty defect), EPC/PLGA (endothelial progenitor cells (EPCs) seeded in the poly lactic-co-glycolic acid (PLGA) scaffold), or EPC/PLGA/CPM (EPC/PLGA scaffold complemented with CPM starting one day after transplantation). We investigated the effects of CPM and the EPC/PLGA constructs on tissue restoration in weight-bearing sites by histological observation and micro-computed tomography (micro-CT) evaluation 4 and 12 weeks after implantation. After CPM, the EPC/PLGA construct exhibited early osteochondral regeneration and prevention of subchondral bone overgrowth and cartilage degeneration. CPM did not alter the microenvironment created by the construct; it up-regulated the expression of the extracellular matrix components (glycosaminoglycan and collagen), down-regulated bone formation, and induced the biosynthesis of lubricin, which appeared in the EPC/PLGA/CPM group after 12 weeks. CPM can provide promoting signals during osteochondral tissue engineering and achieve a synergistic effect when combined with EPC/PLGA transplantation, so it should be considered a non-invasive treatment to be adopted in clinical practices.

Bombyx mori derived scaffolds and their use in cartilage regeneration: a systematic review

For the last two decades, silk has been extensively used as scaffolds in tissue engineering because of its remarkable properties. Unfortunately, the aneural property of cartilage limits its regenerative potential which can be achieved using tissue engineering approach. A lot of research has been published searching for the optimization of silk fibroin (SF) and its blends in order to get the best cartilage mimicking properties. However, according to our best knowledge, there is no systematic review available regarding the use of Bombyx mori derived biomaterials limited to cartilage related studies. This systematic review highlights the in vitro and in vivo work done for the past 7 years on structural and functional properties of B. mori derived biomaterials together with different parameters for cartilage regeneration. PubMed database was searched focusing on in vitro and in vivo studies using the search thread "silk fibroin" and "cartilage". A total of 40 articles met the inclusion criteria. All the articles were deeply studied for cell types, scaffold types and animal models used along with study design and results. Five types of cells were used for in vitro while seven types of cells were used for in vivo studies. Three types of animal models were used for scaffold implantation purpose. Moreover, different types of scaffolds either seeded with cells or supplemented with various factors were explored and discussed in detail. Results suggest the suitability of silk as a better biomaterial because of its cartilage mimicking properties.

Role of Forkhead Box O Transcription Factors in Oxidative Stress-Induced Chondrocyte Dysfunction: Possible Therapeutic Target for Osteoarthritis?

Chondrocyte dysfunction occurs during the development of osteoarthritis (OA), typically resulting from a deleterious increase in oxidative stress. Accordingly, strategies for arresting oxidative stress-induced chondrocyte dysfunction may lead to new potential therapeutic targets for OA treatment. Forkhead box O (FoxO) transcription factors have recently been shown to play a protective role in chondrocyte dysfunction through the regulation of inflammation, autophagy, aging, and oxidative stress. They also regulate growth, maturation, and matrix synthesis in chondrocytes. In this review, we discuss the recent progress made in the field of oxidative stress-induced chondrocyte dysfunction. We also discuss the protective role of FoxO transcription factors as potential molecular targets for the treatment of OA. Understanding the function of FoxO transcription factors in the OA pathology may provide new insights that will facilitate the development of next-generation therapies to prevent OA development and to slow OA progression.

Role of Forkhead Box O Transcription Factors in Oxidative Stress-Induced Chondrocyte Dysfunction: Possible Therapeutic Target for Osteoarthritis?

Chondrocyte dysfunction occurs during the development of osteoarthritis (OA), typically resulting from a deleterious increase in oxidative stress. Accordingly, strategies for arresting oxidative stress-induced chondrocyte dysfunction may lead to new potential therapeutic targets for OA treatment. Forkhead box O (FoxO) transcription factors have recently been shown to play a protective role in chondrocyte dysfunction through the regulation of inflammation, autophagy, aging, and oxidative stress. They also regulate growth, maturation, and matrix synthesis in chondrocytes. In this review, we discuss the recent progress made in the field of oxidative stress-induced chondrocyte dysfunction. We also discuss the protective role of FoxO transcription factors as potential molecular targets for the treatment of OA. Understanding the function of FoxO transcription factors in the OA pathology may provide new insights that will facilitate the development of next-generation therapies to prevent OA development and to slow OA progression.

Recently highlighted nutraceuticals for preventive management of osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disease of articular cartilage with limited treatment options. This reality encourages clinicians to suggest preventive measures to delay and contain the outbreak of the pathological conditions. Articular cartilage and synovium suffering from OA are characterised by an inflammatory state and by significant oxidative stress, responsible for pain, swelling and loss of mobility in the advanced stages. This review will focus on the ability of olive oil to exert positive effects on the entire joint to reduce pro-inflammatory cytokine release and increase lubricin synthesis, olive leaf extract, since it maintains lubrication by stimulating high molecular weight hyaluronan synthesis in synovial cells, curcumin, which delays the start of pathological cartilage breakdown, sanguinarine, which downregulates catabolic proteases, vitamin D for its capacity to influence the oxidative and pro-inflammatory environment, and carnosic acid as an inducer of heme oxygenase-1, which helps preserve cartilage degeneration. These molecules, considered as natural dietary supplements, appear like a cutting-edge answer to this tough health problem, playing a major role in controlling homeostatic balance loss and slowing down the pathology progression. Natural or food-derived molecules that are able to exert potential therapeutic effects are known as “nutraceutical”, resulting from the combination of the words “nutrition” and “pharmaceutical”. These compounds have gained popularity due to their easy availability, which represents a huge advantage for food and pharmaceutical industries. In addition, the chronic nature of OA implies the use of pharmacological compounds with proven long-term safety, especially because current treatments like nonsteroidal anti-inflammatory drugs and analgesics improve pain relief but have no effect on degenerative progression and can also cause serious side effects.

Energy metabolic capacities of human adipose-derived mesenchymal stromal cells in vitro and their adaptations in osteogenic and adipogenic differentiation

Mesenchymal stromal/stem cells (MSC) are important in tissue homeostasis and regeneration due to their ability for self-renewal and multipotent differentiation. Differentiation, as well as proliferation, requires adaptations in the cell metabolism. However, only few data exist concerning the energy metabolism of non-differentiating and differentiating MSC. In this study we compared capacities of major energy metabolic pathways of MSC from human adipose tissue (adMSC) in vitro in the non-differentiated state with those of osteogenically or adipogenically differentiating adMSC. To this end we quantified the proliferation and differentiation status of adMSC and analyzed maximum enzyme capacities and several enzyme isoforms of major energy metabolic pathways regarding their activity and gene expression. We could show that non-differentiating and osteogenic cultivation conditions induced proliferation and showed increasing capacities of the glycolytic marker enzyme phosphofructokinase as well as the marker enzyme of the pentose phosphate pathway glucose-6-phosphate dehydrogenase. Adipogenic stimulation, which was accompanied by the absence of proliferation, reduced the glycolytic capacity (e.g. decreased glyceraldehyde 3-phosphate dehydrogenase capacity) and induced an increase in mitochondrial enzyme capacities. These changes in energy metabolism might represent an adaptation of adMSC to the high energy demand during proliferation and to the specific cellular functions during osteogenic or adipogenic differentiation respectively.

Adipose-derived stem-cell-implanted poly(ϵ-caprolactone)/chitosan scaffold improves bladder regeneration in a rat model

AIM

The study investigated the feasibility of seeding adipose-derived stem cells (ASCs) onto a poly(ϵ-caprolactone)/chitosan (PCL/CS) scaffold for bladder reconstruction using a rat model of bladder augmentation.

MATERIALS & METHODS

In the experimental group, the autologous ASCs were seeded onto the PCL/CS scaffold for bladder augmentation. An unseeded scaffold was used for bladder augmentation as control group. The sham group was also set.

RESULT

8 weeks after implantation, more densely smooth muscles were detected in the experimental group with a larger bladder capacity and more intensive blood vessels. Immunofluorescence staining demonstrated that some of the smooth muscle cells were transdifferentiated from the ASCs.

CONCLUSION

Our findings indicated that ASC-seeded PCL/CS may be a potential scaffold for bladder tissue engineering.

Physiologically based microenvironment for in vitro neural differentiation of adipose-derived stem cells

The limited capacity of nervous system to promote a spontaneous regeneration and the high rate of neurodegenerative diseases appearance are keys factors that stimulate researches both for defining the molecular mechanisms of pathophysiology and for evaluating putative strategies to induce neural tissue regeneration. In this latter aspect, the application of stem cells seems to be a promising approach, even if the control of their differentiation and the maintaining of a safe state of proliferation should be troubled. Here, we focus on adipose tissue-derived stem cells and we seek out the recent advances on the promotion of their neural differentiation, performing a critical integration of the basic biology and physiology of adipose tissue-derived stem cells with the functional modifications that the biophysical, biomechanical and biochemical microenvironment induces to cell phenotype. The pre-clinical studies showed that the neural differentiation by cell stimulation with growth factors benefits from the integration with biomaterials and biophysical interaction like microgravity. All these elements have been reported as furnisher of microenvironments with desirable biological, physical and mechanical properties. A critical review of current knowledge is here proposed, underscoring that a real advance toward a stable, safe and controllable adipose stem cells clinical application will derive from a synergic multidisciplinary approach that involves material engineer, basic cell biology, cell and tissue physiology.

Regulation of lubricin for functional cartilage tissue regeneration: a review

Background

Lubricin is chondrocyte-secreted glycoprotein that primarily conducts boundary lubrication between joint surfaces. Besides its cytoprotective function and extracellular matrix (ECM) attachment, lubricin is recommended as a novel biotherapeutic protein that restore functional articular cartilage. Likewise, malfunction of lubrication in damaged articular cartilage caused by complex and multifaceted matter is a major concern in the field of cartilage tissue engineering.

Main body

Although a noticeable progress has been made toward cartilage tissue regeneration through numerous approaches such as autologous chondrocyte implantation, osteochondral grafts, and microfracture technique, the functionality of engineered cartilage is a challenge for complete reconstruction of cartilage. Thus, delicate modulation of lubricin along with cell/scaffold application will expand the research on cartilage tissue engineering.

Conclusion

In this review, we will discuss the empirical analysis of lubricin from fundamental interpretation to the practical design of gene expression regulation.

The human umbilical cord stem cells improve the viability of OA degenerated chondrocytes

Osteoarthritis (OA) affects a large number of patients; however, human umbilical cord stem cells exhibit therapeutic potential for treating OA. The aim of the present study was to explore the interaction between human umbilical cord stem cells and degenerated chondrocytes, and the therapeutic potential of human umbilical cord stem cells on degenerated chondrocytes. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) were harvested from human umbilical cords, and flow cytometry was used to analyze the surface antigen markers, in addition, chondrogenic, osteogenic and adipogenic differentiation on the cells was investigated. OA cells at P3 were cocultured with hUC-MSCs in a separated co-culture system, and reverse transcription-polymerase chain reaction and western blot were used to evaluate the mRNA, and protein expression of collagen type II (Col2), SRY-box 9 (sox-9) and aggrecan. The level of inflammatory cytokines, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-10, were analyzed by ELISA in the supernatant. hUC-MSCs grow in a fibroblastic shape with stable proliferation. hUC-MSCs expressed cluster of differentiation 44 (CD44), CD73, CD90, CD105; while did not express CD34, CD45, CD106, CD133. After multi-induction, hUC-MSCs were able to differatiate into adipogenic, osteogenic and chondrogenic lineage. hUC-MSCs inhibited the expression of matrix metalloproteinase-13, collagen type X α1 chain and cyclooxygenase-2 in OA chondrocytes, and enhanced the proliferation of OA chondrocytes, while OA chondrocytes stimulated the production of Col2, sox-9 and aggrecan and promoted hUC-MSCs differentiate into chondrocytes. Flow cytometry analysis demonstrated hUC-MSCs have a predominant expression of stem cell markers, while the hematopoietic and endothelial markers were absent. Osteogenic, chondrogenic and adipogenic differentiation was observed in certain induction conditions. hUC-MSCs improved the proliferation of OA chondrocytes and downregulated the expression of inflammatory cytokines, while OA chondrocytes promoted MSCs to differentiate into chondrocytes. Taken together, the co-culture of hUC-MSCs and OA chondrocytes may provide a therapeutic potential in OA treatment.

Natural Type II Collagen Hydrogel, Fibrin Sealant, and Adipose-Derived Stem Cells as a Promising Combination for Articular Cartilage Repair

Objective Articular cartilage is an avascular tissue with limited ability of self-regeneration and the current clinical treatments have restricted capacity to restore damages induced by trauma or diseases. Therefore, new techniques are being tested for cartilage repair, using scaffolds and/or stem cells. Although type II collagen hydrogel, fibrin sealant, and adipose-derived stem cells (ASCs) represent suitable alternatives for cartilage formation, their combination has not yet been investigated in vivo for focal articular cartilage defects. We performed a simple experimental procedure using the combination of these 3 compounds on cartilage lesions of rabbit knees. Design The hydrogel was developed in house and was first tested in vitro for chondrogenic differentiation. Next, implants were performed in chondral defects with or without ASCs and the degree of regeneration was macroscopically and microscopically evaluated. Results Production of proteoglycans and the increased expression of collagen type II (COL2α1), aggrecan (ACAN), and sex-determining region Y-box 9 (SOX9) confirmed the chondrogenic character of ASCs in the hydrogel in vitro. Importantly, the addition of ASC induced a higher overall repair of the chondral lesions and a better cellular organization and collagen fiber alignment compared with the same treatment without ASCs. This regenerating tissue also presented the expression of cartilage glycosaminoglycan and type II collagen. Conclusions Our results indicate that the combination of the 3 compounds is effective for articular cartilage repair and may be of future clinical interest.

The effects of knee immobilization on marrow adipocyte hyperplasia and hypertrophy at the proximal rat tibia epiphysis

Marrow adipose deposition is observed during aging and in association with extended periods of immobility. The objective of this study was to determine the contribution of adipocyte hypertrophy and hyperplasia to bone marrow fat deposition induced by immobilization of the rat knee joint for 2, 4, 16 or 32 weeks. Histomorphometric analyses compared immobilized to sham-operated proximal tibia from age and gender matched rats to assess the contribution of aging and duration of immobilization on the number and size of marrow adipocytes. Results indicated that marrow adipose tissue increased with the duration of immobilization and was significant larger at 16 weeks compared to the sham-operated group (0.09956±0.13276mm² vs 0.01990±0.01100mm², p=0.047). The marrow adipose tissue was characterized by hyperplasia of adipocytes with a smaller average size after 2 and 4 weeks of immobilization (at 2 weeks hyperplasia: 68.86±33.62 vs 43.57±24.47 adipocytes/mm², p=0.048; at 4 weeks hypotrophy: 0.00036±0.00019 vs 0.00046±0.00023mm², p=0.027), and by adipocyte hypertrophy after 16 weeks of immobilization (0.00083±0.00049 vs 0.00046±0.00028mm², p=0.027) compared to sham-operated. Both immobilized and sham-operated groups showed marrow adipose conversion with age; immobilized (p=0.008; sham: p=0.003). Overall, fat deposition in the bone marrow of the proximal rat tibia epiphysis and induced by knee joint immobilization was characterized by hyperplasia of small adipocytes in the early phase and by adipocyte hypertrophy in the later phase. Mediators of marrow fat deposition after immobilization and preventive countermeasures need to be investigated.

Aquaporin1 and 3 modification as a result of chondrogenic differentiation of human mesenchymal stem cell

Chondrocytes are cells of articular cartilage particularly sensitive to water transport and ionic and osmotic changes from extracellular environment and responsible for the production of the synovial fluid. Aquaporins (AQPs) are a family of water and small solute transport channel proteins identified in several tissues, involved in physiological pathways and in manifold human diseases. In a recent period, AQP1 and 3 seem to have a role in metabolic water regulation in articular cartilage of load bearing joints. The aim of this study was to examine the levels of AQP1 and 3 during the chondrogenic differentiation of human mesenchymal stem cells (MSCs) derived from adipose tissue (AT). For the determination of chondrogenic markers and AQPs levels, glycosaminoglycans (GAGs) quantification, immunocytochemistry, RT-PCR, and Western blot were used after 0, 7, 14, 21, and 28 days from the start of differentiation. At 21 days, chondrocytes derived from AT-MSCs were able to produce augmented content of GAGs and significant quantity of SOX-9, lubricin, aggrecan, and collagen type II, suggesting hyaline cartilage formation, in combination with an increase of AQP3 and AQP1. However, while AQP1 level decreased after 21 days; AQP3 reached higher values at 28 days. The expression of AQP1 and 3 is a manifestation of physiological adaptation of functionally mature chondrocytes able to respond to the change of their internal environment influenced by extracellular matrix. The alteration or loss of expression of AQP1 and 3 could contribute to destruction of chondrocytes and to development of cartilage damage.

Mesenchymal Stem Cell-Based Cartilage Regeneration Approach and Cell Senescence: Can We Manipulate Cell Aging and Function?

Aging is the most prominent risk factor triggering several degenerative diseases, such as osteoarthritis (OA). Due to its poor self-healing capacity, once injured cartilage needs to be reestablished. This process might be approached through resorting to cell-based therapies and/or tissue engineering. Human mesenchymal stem cells (MSCs) represent a promising approach due to their chondrogenic differentiation potential. Presently, in vitro chondrogenic differentiation of MSCs is limited by two main reasons as follows: aging of MSCs, which determines the loss of cell proliferative and differentiation capacity and MSC-derived chondrocyte hypertrophic differentiation, which limits the use of these cells in cartilage tissue regeneration approach. The effect of aging on MSCs is fundamental for stem cell-based therapy development, especially in older subjects. In the present review we focus on homeostasis alterations occurring in MSC-derived chondrocytes during in vitro aging. Moreover, we deal with potential cell aging regulation approaches, such as cell stimulation through telomerase activators, mechanical strain, and epigenetic regulation. Future investigations in this field might provide new insights into innovative strategies for cartilage regeneration and potentially inspire novel therapeutic approaches for OA treatment.

Vitamin E protects rat mesenchymal stem cells against hydrogen peroxide-induced oxidative stress in vitro and improves their therapeutic potential in surgically-induced rat model of osteoarthritis

OBJECTIVE

Oxidative stress is a major obstacle against cartilage repair in osteoarthritis (OA). Anti-oxidant agents can play a vital role in addressing this issue. We evaluated the effect of Vitamin E preconditioning in improving the potential of mesenchymal stem cells (MSCs) to confer resistance against oxidative stress prevailing during OA.

METHODS

Vitamin E pretreated MSCs were exposed to oxidative stress in vitro by hydrogen peroxide (H₂O₂) and also implanted in surgically-induced rat model of OA. Analysis was done in terms of cell proliferation, apoptosis, cytotoxicity, chondrogenesis and repair of cartilage tissue.

RESULTS

Vitamin E pretreatment enabled MSCs to counteract H₂O₂-induced oxidative stress in vitro. Proliferative markers, proliferating cell nuclear antigen (PCNA) and Ki67 were up-regulated, along with the increase in the viability of MSCs. Expression of transforming growth factor-beta (TGFβ) was also increased. Reduction of apoptosis, expression of vascular endothelial growth factor (VEGF) and caspase 3 (Casp3) genes, and lactate dehydrogenase (LDH) release were also observed. Transplantation of Vitamin E pretreated MSCs resulted in increased proteoglycan contents of cartilage matrix. Increased expression of chondrogenic markers, Aggrecan (Acan) and collagen type-II alpha (Col2a1) accompanied by decreased expression of collagen type-I alpha (Col1a1) resulted in increased differentiation index that signifies the formation of hyaline cartilage. Further, there was an increased expression of PCNA and TGFβ genes along with a decreased expression of Casp3 and VEGF genes with increased histological score.

CONCLUSION

Taken together results of this study demonstrated that Vitamin E pretreated MSCs have an improved ability to impede the progression of OA and thus increased potential to treat OA.

Human Mesenchymal Stem Cells from Adipose Tissue Differentiated into Neuronal or Glial Phenotype Express Different Aquaporins

Aquaporins (AQPs) are 13 integral membrane proteins that provide selective pores for the rapid movement of water and other uncharged solutes, across cell membranes. Recently, AQPs have been focused for their role in production, circulation, and homeostasis of the cerebrospinal fluid and their importance in several human diseases is becoming clear. This study investigated the time course (0, 14, and 28 days) of AQP1, 4, 7, 8, and 9 during the neural differentiation of human mesenchymal stem cells (MSCs) from adipose tissue (AT). For this purpose, two different media, enriched with serum or B-27 and N1 supplements, were applied to give a stimulus toward neural lineage. After 14 days, the cells were cultured with neuronal or glial differentiating medium for further 14 days. The results confirmed that AT-MSCs could be differentiated into neurons, astrocytes, and oligodendrocytes, expressing not only the typical neural markers but also specific AQPs depending on differentiated cell type. Our data demonstrated that at 28 days, AT-MSCs express only AQP1; astrocytes AQP1, 4, and 7; oligodendrocytes AQP1, 4, and 8; and finally neurons AQP1 and 7. This study provides fundamental insight into the biology of the mesenchymal stem cells and it suggests that AQPs can be potential neural markers.

Potential Therapeutic Applications of Adipose-Derived Mesenchymal Stem Cells

Stem cells are subdivided into two main categories: embryonic and adult stem cells. In principle, pluripotent embryonic stem cells might differentiate in any cell types of the organism, whereas the potential of adult stem cells would be more restricted. Although adult stem cells from bone marrow have been initially the most extensively studied, those derived from human adipose tissue have been lately more widely investigated, because of several advantages. First, they can be easily obtained in large amounts from subcutaneous adipose tissue, with minimal pain and morbidity for the patients during harvesting. In addition, they feature low immunogenicity and can differentiate not only in cells of mesodermal lineage (adipocytes, osteoblasts, chondrocytes and muscle cells), but also in cells of other germ layers, such as neural or epithelial cells. As their multilineage differentiation capabilities are increasingly highlighted, their possible use in cell-based regenerative medicine is now broadly explored. In fact, starting from in vitro observations, many studies have already entered the preclinical and clinical phases. In this review, because of our main scientific interest, adipogenic, osteogenic, chondrogenic, and neurogenic differentiation abilities of adipose-derived mesenchymal stem cells, as well as their possible therapeutic applications, are chiefly focused. In addition, their ability to differentiate toward muscle, epithelial, pancreatic, and hepatic cells is briefly reported.

Asymmetrical seeding of MSCs into fibrin-poly(ester-urethane) scaffolds and its effect on mechanically induced chondrogenesis

Mesenchymal stem cells (MSCs) are currently being investigated as candidate cells for regenerative medicine approaches for the repair of damaged articular cartilage. For these cells to be used clinically, it is important to understand how they will react to the complex loading environment of a joint in vivo. In addition to investigating alternative cell sources, it is also important for the structure of tissue‐engineered constructs and the organization of cells within them to be developed and, if possible, improved. A custom built bioreactor was used to expose human MSCs to a combination of shear and compression loading. The MSCs were either evenly distributed throughout fibrin‐poly(ester‐urethane) scaffolds or asymmetrically seeded with a small proportion seeded on the surface of the scaffold. The effect of cell distribution on the production and deposition of cartilage‐like matrix in response to mechanical load mimicking in vivo joint loading was then investigated. The results show that asymmetrically seeding the scaffold led to markedly improved tissue development based on histologically detectable matrix deposition. Consideration of cell location, therefore, is an important aspect in the development of regenerative medicine approaches for cartilage repair. This is particularly relevant when considering the natural biomechanical environment of the joint in vivo and patient rehabilitation protocols. © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.

A Citrus bergamia Extract Decreases Adipogenesis and Increases Lipolysis by Modulating PPAR Levels in Mesenchymal Stem Cells from Human Adipose Tissue

The aim of this research was to assess the impact of a well-characterized extract from Citrus bergamia juice on adipogenesis and/or lipolysis using mesenchymal stem cells from human adipose tissue as a cell model. To evaluate the effects on adipogenesis, some cell cultures were treated with adipogenic medium plus 10 or 100 μg/mL of extract. To determine the properties on lipolysis, additional mesenchymal stem cells were cultured with adipogenic medium for 14 days and after this time added with Citrus bergamia for further 14 days. To verify adipogenic differentiation, oil red O staining at 7, 14, 21, and 28 days was performed. Moreover, the expression of peroxisome proliferator-activated receptor gamma (PPAR-γ), adipocytes fatty acid-binding protein (A-FABP), adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), monoglyceride lipase (MGL), 5′-adenosine monophosphate-activated protein kinase (AMPK)α1/2, and pAMPKα1/2 was evaluated by Western blot analysis and the release of glycerol by colorimetric assay. Citrus bergamia extract suppressed the accumulation of intracellular lipids in mesenchymal stem cells during adipogenic differentiation and promoted lipolysis by repressing the expression of adipogenic genes and activating lipolytic genes. Citrus bergamia extract could be a useful natural product for improving adipose mobilization in obesity-related disorders.