RESUMO Objetivo: O objetivo deste estudo foi avaliar o potencial osteogênico de células osteoprogenitoras de sangue de cordão umbilical humano e provar sua aplicabilidade como candidato promissor para terapias celulares de reparo ósseo. Métodos: Culturas primárias de células aderentes de sangue de cordão umbilical humano foram expandidas in vitro até a passagem 2 e semeadas para estudo de osteodiferenciação. Análises morfológicas (microscopia de luz), citoquímicas (método de Von Kossa), e funcionais (dosagem de cálcio, atividade de fosfatase alcalina e conteúdo total de proteína na cultura celular) foram conduzidas em 7, 14, 21, e 28 dias após o protocolo de osteoindução. Resultados: A fase proliferativa demonstrou unidades formadoras de colônia em 7 dias. Após osteoindução, a morfologia celular cuboidal similar a osteoblastos em 14 dias e nódulos de mineralização e mudanças bioquímicas (aumento do nível de fosfatase alcalina e depósitos de cálcio) em 21 dias confirmaram o processo de osteodiferenciação. ConclusÕes: A cultura celular de sangue de cordão umbilical humano é uma técnica segura, constituindo-se uma fonte alternativa de células osteoprogenitoras para usos experimentais. Mais testes em animais e ensaios clínicos devem ser conduzidos para validar seu uso e estabelecer controle de qualidade de futuras terapias celulares autólogas ou alogênicas objetivando o reparo ósseo.

ABSTRACT Objective: The aim of this study was to evaluate the osteogenic potential of human umbilical cord blood-derived osteoprogenitor cells and to prove its applicability as a promising candidate for cell-based therapeutics for bone repair. Methods: Primary cultures of human umbilical blood cord adherent cells were expanded in vitro until passage 2 and seeded for osteodifferentiation study. Morphological (light microscopy), cytochemical (Von Kossa's method), and functional analyses (calcium level, alkaline phosphatase activity, and total protein content in cell culture) were carried out 7, 14, 21, and 28 days after the osteoinduction protocol. Results: The proliferative step showed colony-forming units in 7 days. After osteoinduction, cuboidal cellular morphology similar to osteoblasts at 14 days and mineralization nodules and biochemical changes (increased alkaline phosphatase level and calcium deposits) at 21 days confirmed the osteodifferentiation process. Conclusion: Cell culture of human umbilical blood cord is a reliable technique, constituting itself as an alternative source of osteoprogenitor cells for experimental needs. More animal tests and clinical trials must be carried out to validate its use and to establish quality control of future autologous or allogeneic cell-based therapy aimed at bone repair.

The aim of this work was to produce hydroxyapatite (HA) granules containing 0, 0.5, 1 and 5 mol. (%) of strontium (Sr), evaluate the physico-chemical properties and also the cytotoxicity by three different parameters of cell viability (ISO 10993-5, 10993-12). The physico-chemical characterization was carried out by using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and X-ray fluorescence (XRF). The XRD profile presented the main peaks of HA (JCPDS 860740) and the absorption bands of HA were identified by FTIR. The XRF results showed that the strontium concentration was close to the theoretical value. Regarding the cytotoxicity assays, the incorporation of strontium up to 5 mol. (%) to the HA did not affected dehydrogenase activity (XTT, 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide), membrane integrity (neutral red uptake) or DNA contend (incorporation of crystal violet), in relation to HA alone. In conclusion, hydroxyapatite containing from 0.5 to 5 mol. (%) of Sr was successfully produced and presented no cytotoxicity.