Stem cells isolated from the human stromal limbus possess immunosuppressant properties.

PURPOSE: Mesenchymal stromal stem cells (MSC) are non-hemopoietic cells with the capacity to self-renewal and to differentiate into various cell lineages of mesenchymal origin. More recently, the immune regulatory potential of MSC has been focused on. Furthermore, mesenchymal stem cells obtained from diverse tissues possess immunomodulatory properties and inhibit proinflammatory immune reactions. The aim of this study was to determine the immunosuppressive characteristics of mesenchymal stem cells isolated from human limbal (L-MSC) tissue. METHODS: L-MSC were enzymatically obtained from cadaveric sclero-corneal rims and expanded in vitro. The cells were characterized by flow cytometry using specific antibodies to mesenchymal stem cells markers. Clonogenic and tissue transdifferentiation in vitro assays were performed. The effect of L-MSC soluble factors on T cell proliferation was determined by flow cytometry. Cytokines such as transforming growth factor-b1 (TGF-ß1) and Interleukin-10 (IL-10) on supernatants from L-MSC were identified by enzyme-linked immunosorbent assay (ELISA). RESULTS: Herein, we described that L-MSC cells in vitro-expanded were positive for the expression of vimentin, CD29, CD34, CD39, CD73 and CD105 mesenchymal stem cells markers; meanwhile, this cell population was negative to CD45 and HLA-DR hemopoietic markers as well as to cytokeratin expression. Clonogenic assays showed that these cells were able to form colonies. In addition, this L-MSC population had the ability to transdifferentiate into neurons and chondrocytes and to form tubular networks on matrigel in the presence of vascular endothelial growth factor (VEGF). These results indicated that these cells were stem cells. Additionally, soluble factors secreted by L-MSC were capable of mediating the suppression of T-cell receptor (TCR)-engagement lymphocyte proliferation. In an attempt to identify the possible immunosuppressive factors secreted by L-MSC, TGFß1 and IL-10 cytokines were determined in the L-MSC supernatants by ELISA; interestingly, TGFß1 was constitutively secreted by this cell population; in contrast, IL-10 was not detectable. Moreover, TGFßRII neutralizing antibodies were able to revert the TCR-engagement lymphocyte proliferation inhibition mediated by L-MSC. Thus, TGFß1 secreted by L-MSC was able to suppress T cell proliferation. CONCLUSIONS: Taken together these results, explain in part the immunosuppressive features of this cell population obtained from the human limbus. All these characteristics make this cell population an excellent source to be used in the regenerative medicine.

HLA-matched living-related conjunctival limbal allograft for bilateral ocular surface disorders: long-term results / Transplante alogênico inter vivo de limbo conjuntival com pareamento HLA em doenças bilaterais da superfície ocular: resultados em longo prazo

PURPOSE: To evaluate the long-term outcome of HLA-matched lr-CLAL for bilateral ocular surface disorders. METHODS: A retrospective, non-comparative interventional case series study of 39 eyes of 32 patients with bilateral surface disorders and clinical diagnosis of limbal stem cell deficiency who underwent HLA-matched lr-CLAL. Visual acuity (VA), ambulatory vision (> 20/200) and ocular surface stability were evaluated as main outcomes. Donor limbus was obtained from a sibling or a parent of the patient, after an appropriate Class I and II HLA match. RESULTS: One year after surgery, VA improved in 46.2 percent, ambulatory vision was achieved in 48.7 percent and a stable corneal surface was achieved in 84.6 percent of the eyes. At the final follow-up (mean, 48.7 ± 30.6 months), 66.6 percent of the eyes that had gained VA one year after surgery maintained an improved VA (p=0.28), 94.7 percent of eyes that had achieved ambulatory vision one year after surgery maintained 20/200 or better (p<0.001) and 93.9 percent still had a stable corneal surface (p=0.043) at the final follow-up. CONCLUSIONS: HLA-matched lr-CLAL can be an adequate method of treatment for bilateral ocular surface disorders, with a reasonable percentage of success of long-term results.

OBJETIVO: Avaliar os resultados em longo prazo do transplante alogênico inter vivo de limbo conjuntival para doenças bilaterais da superfície ocular com compatibilidade HLA doador-receptor. MÉTODOS: Estudo retrospectivo, não comparativo e intervencionista de 39 olhos de 32 pacientes submetidos a transplante alogênico de limbo com compatibilidade HLA e diagnóstico de deficiência límbica. Foram analisados como desfechos principais acuidade visual, visão ambulatorial (> 20/200) e estabilidade da superfície ocular. Limbo doador foi obtido de parentes do paciente após estudo de compatibilidade HLA classe I e II. RESULTADOS: Com um ano de pós-operatório, a acuidade visual melhorou em 46,2 por cento, visão ambulatorial foi atingida em 48,7 por cento e estabilidade da superfície corneana em 84,6 por cento dos pacientes. Ao final do seguimento (média, 48,7 ± 30,6 meses), 66,6 por cento dos olhos que haviam ganho acuidade visual um ano após a cirurgia mantiveram esta melhora (p=0,28), 94,7 por cento dos olhos que haviam alcançado visão ambulatorial um ano após a cirurgia mantiveram visão de 20/200 ou melhor (p<0,001) e 93,9 por cento ainda tinham superfície corneana estável (p=0,043) ao final do seguimento. CONCLUSÕES: O transplante alogênico inter vivo de limbo conjuntival com compatibilidade HLA revelou-se método adequado no tratamento de doenças bilaterais da superfície ocular, com uma porcentagem significativa de sucesso a longo-prazo.

HLA-matched living-related conjunctival limbal allograft for bilateral ocular surface disorders: long-term results.

PURPOSE: To evaluate the long-term outcome of HLA-matched lr-CLAL for bilateral ocular surface disorders. METHODS: A retrospective, non-comparative interventional case series study of 39 eyes of 32 patients with bilateral surface disorders and clinical diagnosis of limbal stem cell deficiency who underwent HLA-matched lr-CLAL. Visual acuity (VA), ambulatory vision (> or = 20/200) and ocular surface stability were evaluated as main outcomes. Donor limbus was obtained from a sibling or a parent of the patient, after an appropriate Class I and II HLA match. RESULTS: One year after surgery, VA improved in 46.2%, ambulatory vision was achieved in 48.7% and a stable corneal surface was achieved in 84.6% of the eyes. At the final follow-up (mean, 48.7 +/- 30.6 months), 66.6% of the eyes that had gained VA one year after surgery maintained an improved VA (p=0.28), 94.7% of eyes that had achieved ambulatory vision one year after surgery maintained 20/200 or better (p<0.001) and 93.9% still had a stable corneal surface (p=0.043) at the final follow-up. CONCLUSIONS: HLA-matched lr-CLAL can be an adequate method of treatment for bilateral ocular surface disorders, with a reasonable percentage of success of long-term results.

Mucosa specific lymphocytes in the human conjunctiva, corneoscleral limbus and lacrimal gland.

Conjunctiva associated lymphoid tissue shows several similarities to mucosa associated lymphoid tissue of the gut and respiratory tract. These similarities have been described in relation to lymphocyte subpopulations and epithelial cell morphology. However, unlike the lymphoid tissue of the gut and respiratory tract, mucosa specific lymphocytes have not been described in the ocular mucosa. In this study we demonstrated the presence of mucosa specific lymphocytes bearing the Human Mucosal Lymphocyte-1 antigen (beta 7 integrin), in the human conjunctiva, limbus and lacrimal gland. The distribution of this subset of lymphocytes corresponded to the distribution of CD8+ T-cells and was found maximally in the epithelium of the epibulbar conjunctiva and in the lacrimal gland. The Human mucosal lymphocyte antigen may function to determine mucosal homing of this particular subset of CD8+ T-cells, which in turn, may have special function in immunological defense and tolerance mechanisms occurring at mucosal surfaces.