Immunoregulatory properties of mouse limbal stem cells

The novel role of lymphatic vessels in the pathogenesis of ocular diseases

Historically, the eye has been considered as an organ free of lymphatic vessels. In recent years, however, it became evident, that lymphatic vessels or lymphatic-like vessels contribute to several ocular pathologies at various peri- and intraocular locations. The aim of this review is to outline the pathogenetic role of ocular lymphatics, the respective molecular mechanisms and to discuss current and future therapeutic options based thereon. We will give an overview on the vascular anatomy of the healthy ocular surface and the molecular mechanisms contributing to corneal (lymph)angiogenic privilege. In addition, we present (i) current insights into the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea triggered e.g. by inflammation or trauma, (ii) the role of lymphatic vessels in different ocular surface pathologies such as dry eye disease, corneal graft rejection, ocular graft versus host disease, allergy, and pterygium, (iii) the involvement of lymphatic vessels in ocular tumors and metastasis, and (iv) the novel role of the lymphatic-like structure of Schlemm's canal in glaucoma. Identification of the underlying molecular mechanisms and of novel modulators of lymphangiogenesis will contribute to the development of new therapeutic targets for the treatment of ocular diseases associated with pathological lymphangiogenesis in the future. The preclinical data presented here outline novel therapeutic concepts for promoting transplant survival, inhibiting metastasis of ocular tumors, reducing inflammation of the ocular surface, and treating glaucoma. Initial data from clinical trials suggest first success of novel treatment strategies to promote transplant survival based on pretransplant corneal lymphangioregression.

Genetic analysis of allogenic donor cells after successful allo-limbal epithelial transplantation in simple and cultivated limbal epithelial transplantation procedures

This non-comparative cohort study investigated long-term donor cell survival after allogenic simple/cultivated limbal epithelial transplantations (allo-SLET/allo-CLET, respectively) by genetic analysis. Transplanted corneal epithelial cells, which underwent impression cytology and/or corneal-button biopsy, were examined for personal identities of autosomal short-tandem repeats; the percentages of donor cells were calculated based on matching recipient or donor buccal-DNA references. Twelve patients were included; 4 underwent allo-CLET, 8 underwent allo-SLET. Eight patients (67%) had total limbal stem cell deficiency (LSCD). Genetic analysis was performed postoperatively (mean, 55.3 months). Donor cells were detected in 4 of 12 patients (25%), all of whom underwent allo-SLET; 1 patient had a donor genotype and 3 patients had a mixed donor/recipient genotype. The longest time of donor cell detection was 30 months. Seven patients (58%) used systemic immunosuppressives at the time of genetic analysis (mean use, 22.5 months). Allogenic donor cells survived in both procedures for the long term postoperatively, which encourages the long-term use of systemic immunosuppressives. Donor cells may not be the only factor in graft survival, in that most successful cases had a recipient profile. Their presence for a specific time may promote niches for the patients' own cells to repopulate, especially for partial LSCD.

Melanocytes as emerging key players in niche regulation of limbal epithelial stem cells

PURPOSE

Limbal melanocytes (LMel) represent essential components of the corneal epithelial stem cell niche and are known to protect limbal epithelial stem/progenitor cells (LEPCs) from UV damage by transfer of melanosomes. Here, we explored additional functional roles for LMel in niche homeostasis, immune regulation and angiostasis.

METHODS

Human corneoscleral tissues were morphologically analyzed in normal, inflammatory and wound healing conditions. The effects of LMel on LEPCs were analyzed in direct and indirect co-culture models using electron microscopy, immunocytochemistry, qRT-PCR, Western blotting and functional assays; limbal mesenchymal stromal cells and murine embryonic 3T3 fibroblasts served as controls. The immunophenotype of LMel was assessed by flow cytometry before and after interferon-γ stimulation, and their immunomodulatory properties were analyzed by mixed lymphocytes reaction, monocyte adhesion assays and cytometric bead arrays. Their angiostatic effects on human umbilical cord endothelial cells (HUVECs) were evaluated by proliferation, migration, and tube formation assays.

RESULTS

LMel and LEPCs formed structural units in the human limbal stem cell niche in situ, which could be functionally replicated, including melanosome transfer, by co-cultivation in vitro. LMel supported LEPCs during clonal expansion and during epithelial wound healing by stimulating proliferation and migration, and suppressed their differentiation through direct contact and paracrine effects. Under inflammatory conditions, LMel were increased in numbers and upregulated expression of ICAM-1 and MHC II molecules (HLA-DR), but lacked expression of HLA-G, -DP, -DQ and costimulatory molecules CD80 and CD86. They were also found to be potent suppressors of alloreactive T- cell proliferation and cytokine secretion, which largely depended on direct cell-cell interaction. Moreover, the LMel secretome exerted angiostatic activity by inhibiting vascular endothelial cell proliferation and capillary network formation.

CONCLUSION

These findings suggest that LMel are not only professional melanin-producing cells, but exert various non-canonical functions in limbal niche homeostasis by regulating LEPC maintenance, immune responses, and angiostasis. Their potent regulatory, immunomodulatory and anti-angiogenic properties may have important implications for future regenerative cell therapies.

Global Consensus on Definition, Classification, Diagnosis, and Staging of Limbal Stem Cell Deficiency

PURPOSE

Despite extensive knowledge gained over the last 3 decades regarding limbal stem cell deficiency (LSCD), the disease is not clearly defined, and there is lack of agreement on the diagnostic criteria, staging, and classification system among treating physicians and research scientists working on this field. There is therefore an unmet need to obtain global consensus on the definition, classification, diagnosis, and staging of LSCD.

METHODS

A Limbal Stem Cell Working Group was first established by The Cornea Society in 2012. The Working Group was divided into subcommittees. Four face-to-face meetings, frequent email discussions, and teleconferences were conducted since then to obtain agreement on a strategic plan and methodology from all participants after a comprehensive literature search, and final agreement was reached on the definition, classification, diagnosis, and staging of LSCD. A writing group was formed to draft the current manuscript, which has been extensively revised to reflect the consensus of the Working Group.

RESULTS

A consensus was reached on the definition, classification, diagnosis, and staging of LSCD. The clinical presentation and diagnostic criteria of LSCD were clarified, and a staging system of LSCD based on clinical presentation was established.

CONCLUSIONS

This global consensus provides a comprehensive framework for the definition, classification, diagnosis, and staging of LSCD. The newly established criteria will aid in the correct diagnosis and formulation of an appropriate treatment for different stages of LSCD, which will facilitate a better understanding of the condition and help with clinical management, research, and clinical trials in this area.

Limbal stem cells: identity, developmental origin, and therapeutic potential

The cornea is our window to the world and our vision is critically dependent on corneal clarity and integrity. Its epithelium represents one of the most rapidly regenerating mammalian tissues, undergoing full-turnover over the course of approximately 1-2 weeks. This robust and efficient regenerative capacity is dependent on the function of stem cells residing in the limbus, a structure marking the border between the cornea and the conjunctiva. Limbal stem cells (LSC) represent a quiescent cell population with proliferative capacity residing in the basal epithelial layer of the limbus within a cellular niche. In addition to LSC, this niche consists of various cell populations such as limbal stromal fibroblasts, melanocytes and immune cells as well as a basement membrane, all of which are essential for LSC maintenance and LSC-driven regeneration. The LSC niche's components are of diverse developmental origin, a fact that had, until recently, prevented precise identification of molecularly defined LSC. The recent success in prospective LSC isolation based on ABCB5 expression and the capacity of this LSC population for long-term corneal restoration following transplantation in preclinical in vivo models of LSC deficiency underline the considerable potential of pure LSC formulations for clinical therapy. Additional studies, including genetic lineage tracing of the developmental origin of LSC will further improve our understanding of this critical cell population and its niche, with important implications for regenerative medicine. WIREs Dev Biol 2018, 7:e303. doi: 10.1002/wdev.303 This article is categorized under: Adult Stem Cells, Tissue Renewal, and Regeneration > Stem Cells and Disease Adult Stem Cells, Tissue Renewal, and Regeneration > Tissue Stem Cells and Niches Adult Stem Cells, Tissue Renewal, and Regeneration > Regeneration.

Cell Adhesion Molecules and Stem Cell-Niche-Interactions in the Limbal Stem Cell Niche

Interactions between stem cells and their microenvironment are critical for regulation and maintenance of stem cell function. To elucidate the molecular interactions within the human limbal epithelial stem/progenitor cell (LEPC) niche, which is essential for maintaining corneal transparency and vision, we performed a comprehensive expression analysis of cell adhesion molecules (CAMs) using custom-made quantitative real-time polymerase chain reaction (qRT-PCR) arrays and laser capture-microdissected LEPC clusters, comprising LEPCs, melanocytes, mesenchymal cells, and transmigrating immune cells. We show that LEPCs are anchored to their supporting basement membrane by the laminin receptors α3β1 and α6β4 integrin and the dystroglycan complex, while intercellular contacts between LEPCs and melanocytes are mediated by N-, P-, and E-cadherin together with L1-CAM, a member of the immunoglobulin superfamily (Ig)CAMs. In addition to the LEPC-associated heparan sulfate proteoglycans syndecan-2, glypican-3, and glypican-4, the IgCAM members ICAM-1 and VCAM-1 were found to be variably expressed on LEPCs and associated niche cells and to be dynamically regulated in response to chemokines such as interferon-γ to enhance interactions with immune cells. Moreover, junctional adhesion molecule JAM-C accumulating in the subepithelial limbal matrix, appeared to be involved in recruitment of immune cells, while mesenchymal stromal cells appeared to use the nephronectin receptor integrin α8 for approaching the limbal basement membrane. In summary, we identified a novel combination of cell surface receptors that may regulate both stable and dynamic cell-matrix and cell-cell interactions within the limbal niche. The findings provide a solid foundation for further functional studies and for advancement of our current therapeutic strategies for ocular surface reconstruction.

A Comparative Study of the Therapeutic Potential of Mesenchymal Stem Cells and Limbal Epithelial Stem Cells for Ocular Surface Reconstruction

Stem cell-based therapy has become an attractive and promising approach for the treatment of severe injuries or thus-far incurable diseases. However, the use of stem cells is often limited by a shortage of available tissue-specific stem cells; therefore, other sources of stem cells are being investigated and tested. In this respect, mesenchymal stromal/stem cells (MSCs) have proven to be a promising stem cell type. In the present study, we prepared MSCs from bone marrow (BM-MSCs) or adipose tissue (Ad-MSCs) as well as limbal epithelial stem cells (LSCs), and their growth, differentiation, and secretory properties were compared. The cells were grown on nanofiber scaffolds and transferred onto the alkali-injured eye in a rabbit model, and their therapeutic potential was characterized. We found that BM-MSCs and tissue-specific LSCs had similar therapeutic effects. Clinical characterization of the healing process, as well as the evaluation of corneal thickness, re-epithelialization, neovascularization, and the suppression of a local inflammatory reaction, were comparable in the BM-MSC- and LSC-treated eyes, but results were significantly better than in injured, untreated eyes or in eyes treated with a nanofiber scaffold alone or with a nanofiber scaffold seeded with Ad-MSCs. Taken together, the results show that BM-MSCs' therapeutic effect on healing of injured corneal surface is comparable to that of tissue-specific LSCs. We suggest that BM-MSCs can be used for ocular surface regeneration in cases when autologous LSCs are absent or difficult to obtain.

SIGNIFICANCE

Damage of ocular surface represents one of the most common causes of impaired vision or even blindness. Cell therapy, based on transplantation of stem cells, is an optimal treatment. However, if limbal stem cells (LSCs) are not available, other sources of stem cells are tested. Mesenchymal stem cells (MSCs) are a convenient type of cell for stem cell therapy. The therapeutic potential of LSCs and MSCs was compared in an experimental model of corneal injury, and healing was observed following chemical injury. MSCs and tissue-specific LSCs had similar therapeutic effects. The results suggest that bone marrow-derived MSCs can be used for ocular surface regeneration in cases when autologous LSCs are absent or difficult to obtain.

Immunogenicity and escape mechanisms of allogeneic tendon-derived stem cells

The immunogenicity of tendon-derived stem cells (TDSCs) has implications for their clinical use for the promotion of tendon repair. The immunogenicity and escape mechanisms of rat patellar TDSCs were examined after allogeneic transplantation. Our results showed that TDSCs exhibited low immunogenicity as evidenced by the following: (i) the incubation of target TDSCs with immunized serum did not show antibody recognition and did not induce the complement-dependent cytotoxicity; (ii) target TDSCs elicited a very low level of lymphocyte proliferation and did not exhibit host lymphocyte-mediated cytotoxicity; and (iii) target TDSCs dose dependently suppressed the phorbol 12-myristate 13-acetate (PMA)- and ionomycin-induced host lymphocyte proliferation. For the mechanistic studies, TDSCs expressed major histocompatibility complex (MHC)-I but a very low level of MHC-II, CD86 and CD80 for the induction of T-cell response. Also, TDSCs were found to express intracellular Fas and FasL. γ-IFN pretreatment did not increase the level of MHC-II and CD86 for the upregulation of immune response. Moreover, the immunosuppressive mediators indoleamine 2,3-dioxygenase (IDO) and transforming growth factor-beta 1 (TGF-β1) were found not to be involved in the escape mechanism of target TDSCs from host lymphocyte attack. In conclusion, allogeneic TDSCs exhibited low immunogenicity. Allogeneic TDSCs might be used for transplantation.

Allogeneic tendon-derived stem cells promote tendon healing and suppress immunoreactions in hosts: in vivo model

The medium- to long-term healing effect and infiltration of inflammatory cells, after transplantation of allogeneic tendon-derived stem cell (TDSC) to the rat patellar tendon window wound, were examined. Allogeneic patellar TDSCs derived from a green fluorescent protein rat were used. The outcome of tendon healing and the infiltration of inflammatory cells were examined by histology and immunohistochemistry up to week 16 postinjury. The fate of the transplanted cells was examined by ex vivo fluorescent imaging and immunohistochemistry. Our results showed that the transplantation of allogeneic TDSCs promoted tendon healing with no increased risk of ectopic chondro-ossification up to week 16. A low infiltration of T cells, ED1 macrophages, ED2 macrophages, and mast cells in the window wound was obtained. The transplanted TDSCs were found in the window wound at week 1 and 2, but were absent after week 4 postinjury. In conclusion, allogeneic TDSCs promoted tendon repair in the medium to long term and exhibited weak immunoreactions and anti-inflammatory effects in the hosts after transplantation in a rat model. There was no increased risk of ectopic chondro-ossification after TDSC transplantation. The decrease in the number of transplanted cells with time suggested that allogeneic TDSCs did not promote tendon repair through direct differentiation.

Mesenchymal stem cells, nanofiber scaffolds and ocular surface reconstruction

Ocular surface defects represent one of the most common causes of impaired vision or even blindness. For treatment, keratoplasty represents the first choice. However, if corneal defects are more extensive and associated with a limbal stem cell (LSC) deficiency, corneal transplantation is not a sufficient therapeutic procedure and only viable approach to treatment is the transplantation of LSCs. When the LSC deficiency is a bilateral disorder, autologous LSCs are not available. The use of allogeneic LSCs requires strong immunosuppression, which leads to side-effects, and the treatment is not always effective. The alternative and perspective approach to the treatment of severe ocular surface injuries and LSC deficiency is offered by the transplantation of autologous mesenchymal stem cells (MSCs). These cells can be obtained from the bone marrow or adipose tissue of the particular patient, grow well in vitro and can be transferred, using an appropriate scaffold, onto the damaged ocular surface. Here they exert beneficial effects by possible direct differentiation into corneal epithelial cells, by immunomodulatory effects and by the production of numerous trophic and growth factors. Recent experiments utilizing the therapeutic properties of MSCs in animal models with a mechanically or chemically injured ocular surface have yielded promising results and demonstrated significant corneal regeneration, improved corneal transparency and a rapid healing process associated with the restoration of vision. The use of autologous MSCs thus represents a promising therapeutic approach and offers hope for patients with severe ocular surface injuries and LSC deficiency.

Immunosuppressive properties of mesenchymal stromal cell cultures derived from the limbus of human and rabbit corneas

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) cultivated from the corneal limbus (L-MSCs) provide a potential source of cells for corneal repair. In the present study, we investigated the immunosuppressive properties of human L-MSCs and putative rabbit L-MSCs to develop an allogeneic therapy and animal model of L-MSC transplantation.

METHODS

MSC-like cultures were established from the limbal stroma of human and rabbit (New Zealand white) corneas using either serum-supplemented medium or a commercial serum-free MSC medium (MesenCult-XF Culture Kit; Stem Cell Technologies, Melbourne, Australia). L-MSC phenotype was examined by flow cytometry. The immunosuppressive properties of L-MSC cultures were assessed using mixed leukocyte reactions. L-MSC cultures were also tested for their ability to support colony formation by primary limbal epithelial (LE) cells.

RESULTS

Human L-MSC cultures were typically CD34⁻, CD45⁻ and HLA-DR⁻ and CD73⁺, CD90⁺, CD105⁺ and HLA-ABC⁺. High levels (>80%) of CD146 expression were observed for L-MSC cultures grown in serum-supplemented medium but not cultures grown in MesenCult-XF (approximately 1%). Rabbit L-MSCs were approximately 95% positive for major histocompatibility complex class I and expressed lower levels of major histocompatibility complex class II (approximately 10%), CD45 (approximately 20%), CD105 (approximately 60%) and CD90 (<10%). Human L-MSCs and rabbit L-MSCs suppressed human T-cell proliferation by up to 75%. Conversely, L-MSCs from either species stimulated a 2-fold to 3-fold increase in LE cell colony formation.

CONCLUSIONS

L-MSCs display immunosuppressive qualities in addition to their established non-immunogenic profile and stimulate LE cell growth in vitro across species boundaries. These results support the potential use of allogeneic L-MSCs in the treatment of corneal disorders and suggest that the rabbit would provide a useful pre-clinical model.

Concise review: immunological properties of ocular surface and importance of limbal stem cells for transplantation

Cornea transplantation has been considered to be different from other solid organ transplantation because of the assumed immune-privileged state of the anterior chamber of the eye. Three major lines of thought regarding the molecular mechanisms of immune privilege in the eye are as follows: (a) anatomical, cellular, and molecular barriers in the eye; (b) anterior chamber-associated immune deviation; and (c) immunosuppressive microenvironment in the eye. However, cornea transplants suffer allograft rejection when breached by vascularization. In recent developments, cellular corneal transplantation from cultivated limbal epithelial cells has shown impressive advances as a future therapy. The limbal stem cell niche contains stem cells that promote proliferation and migration and have immunosuppressive mechanisms to protect them from immunological reactions. Limbal stem cells are also noted to display an enhanced expression of genes for the antiapoptotic proteins, a property that is imperative for the survival of transplanted tissues. Further investigation of the molecular mechanisms regulating the immune regulation of limbal stem cells is relevant in the clinical setting to promote the survival of whole corneal and limbal stem cell transplantation.

Human limbal epithelial progenitor cells express αvβ5-integrin and the interferon-inducible chemokine CXCL10/IP-10

Stem cell (SC) therapy is the main treatment modality for patients with limbal stem cell deficiency. If limbal epithelial stem cells (LESC) can be more readily identified, isolated and maintained ex vivo, patients could be treated with better quality grafts. With prior knowledge that vitronectin (VN) is present within the LESC niche and that it supports LESC in vitro, we postulated that VN receptors (integrins αvβ3/5) are expressed by, and can be used to identify and isolate LESC. Immunolocalization studies were conducted on human corneas. Corneas were also used to expand limbal epithelial cells from either biopsies or enzyme-dissociated tissue and αvβ3/5 expression determined by flow cytometry. Integrin expressing cells were isolated by magnetic activated cell sorting then assessed by immunocytology, colony forming efficiency, RT-PCR and microarray analysis. Integrin αvβ5(+) cells co-localized to N-cadherin(+)/CK-15(+) putative LESC. αvβ5 was restricted to less than 4% of the total limbal epithelial cells, which expressed higher levels of CK-15 and formed more colonies compared to αvβ5(-) cells. Transcriptional profiling of αvβ5(+/-) cells by microarray identified several highly expressed interferon-inducible genes, which localize to putative LESC. Integrin αvβ5 is a candidate LESC marker since its expression is restricted to the limbus and αvβ5(+) limbal epithelial cells have phenotypic and functional properties of LESC. Knowledge of the niche's molecular composition and the genes expressed by its SC will facilitate isolation and maintenance of these cells for therapeutic purposes.

The key role of insulin-like growth factor I in limbal stem cell differentiation and the corneal wound-healing process

Limbal stem cells (LSC), which reside in the basal layer of the limbus, are thought to be responsible for corneal epithelial healing after injury. When the cornea is damaged, LSC start to proliferate, differentiate, and migrate to the site of injury. To characterize the signaling molecules ensuring communication between the cornea and LSC, we established a mouse model of mechanical corneal damage. The central cornea or limbal tissue was excised at different time intervals after injury, and the expression of genes in the explants was determined. It was observed that a number of genes for growth and differentiation factors were significantly upregulated in the cornea rapidly after injury. The ability of these factors to regulate the differentiation and proliferation of limbal cells was tested. It was found that the insulin-like growth factor-I (IGF-I), which is rapidly overexpressed after injury, enhances the expression of IGF receptor in limbal cells and induces the differentiation of LSC into cells expressing the corneal cell marker, cytokeratin K12, without any effect on limbal cell proliferation. In contrast, the epidermal growth factor (EGF) and fibroblast growth factor-β (FGF-β), which are also produced by the damaged corneal epithelium, supported limbal cell proliferation without any effect on their differentiation. Other factors did not affect limbal cell differentiation or proliferation. Thus, IGF-I was identified as the main factor stimulating the expression of IGF receptors in limbal cells and inducing the differentiation of LSC into cells expressing corneal epithelial cell markers. The proliferation of these cells was supported by EGF and FGF.

The role of mouse mesenchymal stem cells in differentiation of naive T-cells into anti-inflammatory regulatory T-cell or proinflammatory helper T-cell 17 population

Bone marrow-derived mesenchymal stem cells (MSCs) modulate immune response and can produce significant levels of transforming growth factor-β (TGF-β) and interleukin-6 (IL-6). These 2 cytokines represent the key factors that reciprocally regulate the development and polarization of naive T-cells into regulatory T-cell (Treg) population or proinflammatory T helper 17 (Th17) cells. In the present study we demonstrate that MSCs and their products effectively regulate expression of transcription factors Foxp3 and RORγt and control the development of Tregs and Th17 cells in a population of alloantigen-activated mouse spleen cells or purified CD4(+)CD25(-) T-cells. The immunomodulatory effects of MSCs were more pronounced when these cells were stimulated to secrete TGF-β alone or TGF-β together with IL-6. Unstimulated MSCs produce TGF-β, but not IL-6, and the production of TGF-β can be further enhanced by the anti-inflammatory cytokines IL-10 or TGF-β. In the presence of proinflammatory cytokines, MSCs secrete significant levels of IL-6, in addition to a spontaneous production of TGF-β. MSCs producing TGF-β induced preferentially expression of Foxp3 and activation of Tregs, whereas MSC supernatants containing TGF-β together with IL-6 supported RORγt expression and development of Th17 cells. The effects of MSC supernatants were blocked by the inclusion of neutralization monoclonal antibody anti-TGF-β or anti-IL-6 into the culture system. The results showed that MSCs represent important players that reciprocally regulate the development and differentiation of uncommitted naive T-cells into anti-inflammatory Foxp3(+) Tregs or proinflammatory RORγt(+) Th17 cell population and thereby can modulate autoimmune, immunopathological, and transplantation reactions.

Cyclosporine A-loaded and stem cell-seeded electrospun nanofibers for cell-based therapy and local immunosuppression

Cyclosporine A (CsA), a potent immunosuppressive drug with low water solubility, was dissolved in poly(L-lactic acid) (PLA) solution, and nanofibers were fabricated from this mixture by electrospinning technology. The addition of CsA into the PLA solution and the conditions of the electrospinning process did not influence the structure of the nanofibers nor affect the pharmacological activity of CsA. Study of the CsA release behavior in culture medium showed a release for at least 96 h. After the topical application of CsA-loaded nanofibers on skin allografts in vivo, the release was significantly slower and about 35% of the drug was still retained in the nanofibers on day 8. The addition of CsA-loaded nanofibers into cultures of mouse spleen cells stimulated with Concanavalin A selectively inhibited T cell functions; the activity of stimulated macrophages or the growth of non-T-cell populations was not suppressed in the presence of CsA-loaded nanofibers. The covering of skin allografts with CsA-loaded nanofibers significantly attenuated the local production of the proinflammatory cytokines IL-2, IFN-γ and IL-17. These results suggest that CsA-loaded electrospun nanofibers can serve as effective drug carriers for the local/topical suppression of an inflammatory reaction and simultaneously could be used as scaffolds for cell-based therapy.