Immune modulation with primed mesenchymal stem cells delivered via biodegradable scaffold to repair an Achilles tendon segmental defect

The therapeutic potential of the mesenchymal stem cell secretome in ischaemic stroke

Mesenchymal stem cells (MSCs) hold great potential as a regenerative therapy for stroke, leading to increased repair and functional recovery in animal models of cerebral ischaemia. While it was initially hypothesised that cell replacement was an important mechanism of action of MSCs, focus has shifted to their paracrine actions or the so called "bystander" effect. MSCs secrete a wide array of growth factors, chemokines, cytokines and extracellular vesicles, commonly referred to as the MSC secretome. There is evidence suggesting the MSC secretome can promote repair through a number of mechanisms including preventing cell apoptosis, modulating the inflammatory response and promoting endogenous repair mechanisms such as angiogenesis and neurogenesis. In this review, we will discuss the in vitro approaches currently being employed to drive the MSC secretome towards a more anti-inflammatory and regenerative phenotype. We will then examine the role of the secretome in promoting repair and improving recovery in preclinical models of cerebral ischaemia.

Impact of bone marrow mesenchymal stem cell immunomodulation on the osteogenic effects of laponite

BACKGROUND

With the development of osteoimmunology and bone tissue engineering (BTE), it has been recognized that the immunomodulatory properties of bone biomaterials have considerable impact in determining their fate after implantation. In this regard, the polarization of macrophages secondary to biomaterials is postulated to play a crucial role in modulating their osteogenesis; thus, strategies that may facilitate this process engender increasing levels of attention. Whereas a variety of reports highlight the immunomodulation of bone marrow mesenchymal stem cells (BMSCs) in cell therapy or their osteogenesis in BTE, few have focused on the effect of BMSCs in promoting osteogenesis in BTE through regulating the phenotype of macrophages. Accordingly, there is an urgent need to clarify the immunomodulatory properties of agents such as laponite (Lap), which is comprised of bioactive silicate nanoplatelets with excellent osteogenesis-inducing potential, to enhance their use in BTE.

METHODS

In the present study, we analyzed the osteoimmunomodulatory properties of Lap alone, as well as following the introduction of BMSCs into Lap, to determine whether BMSCs could modulate its immunomodulatory properties and promote osteogenesis.

RESULTS

It was found that the BMSCs reversed the polarization of murine-derived macrophage RAW 264.7 cells from M1 as induced by pure Lap to M2 and promoted osteogenesis. In vivo study confirmed that BMSCs combined with Lap initiated a less severe immune response and had an improved effect on bone regeneration compared with Lap alone, which corresponded with the in vitro evaluation.

CONCLUSION

These results suggest that BMSCs could ameliorate the inflammation induced by Lap and enhance its bone formation. The immunomodulatory characteristics of BMSCs suggest that these might be tailored as a new strategy to promote the osteogenic capacity of biomaterials.

Mesenchymal Stromal Cells Support Endometriotic Stromal Cells In Vitro

Endometriosis is an inflammatory disease marked by ectopic growth of endometrial cells. Mesenchymal stromal cells (MSC) have immunosuppressive properties that have been suggested as a treatment for inflammatory diseases. Therefore, the aim herein was to examine effects of allogeneic MSC on endometriosis-derived cells in vitro as a potential therapy for endometriosis. MSC from allogeneic adipose tissue (Ad-MSC) and stromal cells from endometrium (ESC_endo) and endometriotic ovarian cysts (ESC_cyst) from women with endometriosis were isolated. The effects of Ad-MSC on ESC_endo and ESC_cyst were investigated using in vitro proliferation, apoptosis, adhesion, tube formation, migration, and invasion assays. Ad-MSC significantly increased proliferation of ESC compared to untreated controls. Moreover, Ad-MSC significantly decreased apoptosis and increased survival of ESC. Ad-MSC significantly increased adhesion of ESC_endo and not ESC_cyst on fibronectin. Conditioned medium from cocultures of Ad-MSC and ESC significantly increased tube formation of human umbilical vein endothelial cells on matrigel. Ad-MSC may significantly increase migration of ESC_cyst and did not increase invasion of both cell types. The data suggest that allogeneic Ad-MSC should not be considered as a potential therapy for endometriosis, because they may support the pathology by maintaining and increasing growth of ectopic endometrial tissue.

Preconditioning of murine mesenchymal stem cells synergistically enhanced immunomodulation and osteogenesis

Background

Mesenchymal stem cells (MSCs) are capable of immunomodulation and tissue regeneration, highlighting their potential translational application for treating inflammatory bone disorders. MSC-mediated immunomodulation is regulated by proinflammatory cytokines and pathogen-associated molecular patterns such as lipopolysaccharide (LPS). Previous studies showed that MSCs exposed to interferon gamma (IFN-γ) and the proinflammatory cytokine tumor necrosis factor alpha (TNF-α) synergistically suppressed T-cell activation.

Methods

In the current study, we developed a novel preconditioning strategy for MSCs using LPS plus TNF-α to optimize the immunomodulating ability of MSCs on macrophage polarization.

Results

Preconditioned MSCs enhanced anti-inflammatory M2 macrophage marker expression (Arginase 1 and CD206) and decreased inflammatory M1 macrophage marker (TNF-α/IL-1Ra) expression using an in-vitro coculture model. Immunomodulation of MSCs on macrophages was significantly increased compared to the combination of IFN-γ plus TNF-α or single treatment controls. Increased osteogenic differentiation including alkaline phosphate activity and matrix mineralization was only observed in the LPS plus TNF-α preconditioned MSCs. Mechanistic studies showed that increased prostaglandin E2 (PGE2) production was associated with enhanced Arginase 1 expression. Selective cyclooxygenase-2 inhibition by Celecoxib decreased PGE2 production and Arginase 1 expression in cocultured macrophages.

Conclusions

The novel preconditioned MSCs have increased immunomodulation and bone regeneration potential and could be applied to the treatment of inflammatory bone disorders including periprosthetic osteolysis, fracture healing/nonunions, and osteonecrosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0730-z) contains supplementary material, which is available to authorized users.

Targeting Inflammation in Rotator Cuff Tendon Degeneration and Repair

Rotator cuff degeneration is a common affliction that results in pain and disability. Tendinopathy was historically classified with or without the involvement of the immune system. However, technological advancements in screening have shown that the immune system is both present and active in all forms of tendinopathy. During injury and healing, the coordinated effort of numerous immune cell populations work with the resident stromal cells to break down damaged tissues and stimulate remodeling. These cells deploy a wide array of tools, including phagocytosis, enzyme secretion, and chemotactic gradients to direct these processes. Yet, there remains a knowledge gap in our understanding of the sequence of critical events and regulatory factors that mediate this is process in injury and healing. Furthermore, current treatments do not specifically target inflammation at the molecular level. Typical regimens include non-steroidal anti-inflammatory drugs or corticosteroids; however, researchers have found irrevocable functional deficits following treatment, and have disputed their long-term efficacy. Therefore, developing therapeutics that specifically consider the nuances of the immune system are necessary to improve patient outcomes.

Galectin-1 promotes an M2 macrophage response to polydioxanone scaffolds

Regulating soft tissue repair to prevent fibrosis and promote regeneration is central to creating a microenvironment conducive to soft tissue development. Macrophages play an important role in this process. The macrophage response can be modulated using biomaterials, altering cytokine and growth factor secretion to promote regeneration. Electrospun polydioxanone (PDO) fiber scaffolds promoted an M2 phenotype when macrophages were cultured on large diameter, highly porous scaffolds, but an M1 phenotype on smaller diameter fibers. In this study, we investigated whether incorporation of galectin-1, an immunosuppressive protein that enhances muscle regeneration, could promote the M2 response. Galectin-1 was incorporated into large and small fiber PDO scaffolds during electrospinning. Galectin-1 incorporation increased arginase-1 and reduced iNOS and IL-6 production in mouse bone-marrow derived macrophages compared with PDO alone for both scaffold types. Inhibition of ERK mitogen-activated protein kinase did not alter galectin-1 effects on arginase-1 and iNOS expression, but reversed IL-6 suppression, indicating that IL-6 is mediated by a different mechanism. Our results suggest that galectin-1 can be used to modulate macrophage commitment to a pro-regenerative M2 phenotype, which may positively impact tissue regeneration when using small diameter PDO scaffolds. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2562-2571, 2017.

Bmp-12 activates tenogenic pathway in human adipose stem cells and affects their immunomodulatory and secretory properties

BACKGROUND

Cell-based therapy is a treatment method in tendon injuries. Bone morphogenic protein 12 (BMP-12) possesses tenogenic activity and was proposed as a differentiating factor for stem cells directed to transplantation. However, BMPs belong to pleiotropic TGF-β superfamily and have diverse effect on cells. Therefore, the aim of this study was to determine if BMP-12 induces tenogenic differentiation of human adipose stem cells (hASCs) and how it affects other features of this population.

RESULTS

Human ASCs from 6 healthy donors were treated or not with BMP-12 (50 or 100 ng/ml, 7 days) and tested for gene expression (COLL1, SCX, MKH, DCN, TNC, RUNX2), protein expression (COLL1, COLL3, MKH), proliferation, migration, secretory activity, immunomodulatory properties and susceptibility to oxidative stress. RT-PCR revealed up-regulation of SCX, MKH and RUNX2 genes in BMP-12 treated cells (2.05, 2.65 and 1.87 fold in comparison to control, respectively, p < 0.05) and Western Blot revealed significant increase of COLL1 and MHK expression after BMP-12 treatment. Addition of BMP-12 significantly enhanced secretion of VEGF, IL-6, MMP-1 and MPP-8 by hASCs while had no effect on TGF-β, IL-10, EGF and MMP-13. Moreover, BMP-12 presence in medium attenuated inhibitory effect of hASCs on allo-activated lymphocytes proliferation. At the same time BMP-12 displayed no influence on hASCs proliferation, migration and susceptibility to oxidative stress.

CONCLUSION

BMP-12 activates tenogenic pathway in hASCs but also affects secretory activity and impairs immunomodulatory potential of this population that can influence the clinical outcome after cell transplantation.

Mesenchymal stem cells-derived exosomal microRNAs contribute to wound inflammation

Clinical and experimental studies have highlighted the significance of inflammation in coordinating wound repair and regeneration. However, it remains challenging to control the inflammatory response and tolerance at systemic levels without causing toxicity to injured tissues. Mesenchymal stem cells (MSCs) possess potent immunomodulatory properties and facilitate tissue repair by releasing exosomes, which generate a suitable microenvironment for inflammatory resolution. Exosomes contain several effective bioactive molecules and act as a cell-cell communication vehicle to influence cellular activities in recipient cells. During this process, the horizontal transfer of exosomal microRNAs (miRNAs) to acceptor cells, where they regulate target gene expression, is of particular interest for understanding the basic biology of inflammation ablation, tissue homeostasis, and development of therapeutic approaches. In this review, we describe a signature of three specific miRNAs (miR-21, miR-146a, and miR-181) present in human umbilical cord MSC-derived exosomes (MSC-EXO) identified microarray chip analysis and focus on the inflammatory regulatory functions of these immune-related miRNAs. We also discuss the potential mechanisms contributing to the resolution of wound inflammation and tissue healing.