RESUMO
Stimulation of endogenous neural stem/progenitor cells (NSPCs) with therapeutic factors holds potential for the treatment of stroke. Cyclosporin A (CsA) is a particularly promising candidate molecule because it has been shown to act as a survival factor for these cells over a period of weeks both in vitro and in vivo; however, systemically-delivered CsA compromises the entire immune system, necessitating sustained localized delivery. Herein we describe a local delivery strategy for CsA using an epi-cortical hydrogel of hyaluronan-methylcellulose (HAMC) as the drug reservoir. Three methods of incorporating the drug into the hydrogel (solubilized, particulate, and poly(lactic-co-glycolic) acid (PLGA) microsphere-encapsulated) resulted in tunable release, spanning a period of hours to weeks. Importantly, PLGA-encapsulated CsA released from the hydrogel had equivalent bioactivity to fresh drug as measured by the neurosphere assay. Moreover, when CsA was released from the PLGA/HAMC composite that was injected on the cortex of adult mice, CsA was detected in the NSPC niche at a constant concentration for at least 24days post-implant. Thus this hydrogel composite system may be promising for the treatment of stroke.
Assuntos
Encéfalo/metabolismo , Ciclosporina/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Células-Tronco Neurais/efeitos dos fármacos , Acidente Vascular Cerebral/terapia , Animais , Encéfalo/citologia , Encéfalo/patologia , Cromatografia Líquida , Ciclosporina/líquido cefalorraquidiano , Ciclosporina/farmacocinética , Ciclosporina/uso terapêutico , Preparações de Ação Retardada , Ácido Hialurônico/química , Hidrogéis/química , Ácido Láctico/química , Metilcelulose/química , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Eletrônica de Varredura , Microesferas , Modelos Biológicos , Células-Tronco Neurais/citologia , Tamanho da Partícula , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Solubilidade , Acidente Vascular Cerebral/líquido cefalorraquidiano , Acidente Vascular Cerebral/tratamento farmacológico , Acidente Vascular Cerebral/patologia , Propriedades de Superfície , Espectrometria de Massas em Tandem , Fatores de TempoRESUMO
No effective clinical treatment currently exists for traumatic spinal cord injury. Cell replacement therapy holds promise for attaining functional repair. Cells may be delivered directly or near the injury site; however, this strategy requires a delivery vehicle to maintain cell viability. We have identified an injectable, biocompatible, and biodegradable hydrogel scaffold composed of hyaluronan (HA) and methylcellulose (MC) that may be an effective scaffold for therapeutic cell delivery. The purpose of the present study was to determine the effects of polymer concentration on HAMC mechanical strength, gelation time, and cell viability. The yield stress of HAMC, a measure of mechanical stiffness, was tunable via manipulation of MC and HA content. Measurement of the elastic and storage moduli as functions of time revealed that HAMC gels in less than 5 min at physiological temperatures. Human umbilical tissue-derived cells encapsulated in HAMC were homogenously and stably distributed over 3 days in culture and extended processes into the scaffold. Cell viability was stable over this period in all but the most concentrated HAMC formulation. Because of its strength-tunability, rapid gelation, and ability to maintain cell viability, HAMC is a promising vehicle for cell delivery and is being tested in ongoing in vivo studies.
