A biomaterial with a channel-like pore architecture induces endochondral healing of bone defects.

Biomaterials developed to treat bone defects have classically focused on bone healing via direct, intramembranous ossification. In contrast, most bones in our body develop from a cartilage template via a second pathway called endochondral ossification. The unsolved clinical challenge to regenerate large bone defects has brought endochondral ossification into discussion as an alternative approach for bone healing. However, a biomaterial strategy for the regeneration of large bone defects via endochondral ossification is missing. Here we report on a biomaterial with a channel-like pore architecture to control cell recruitment and tissue patterning in the early phase of healing. In consequence of extracellular matrix alignment, CD146+ progenitor cell accumulation and restrained vascularization, a highly organized endochondral ossification process is induced in rats. Our findings demonstrate that a pure biomaterial approach has the potential to recapitulate a developmental bone growth process for bone healing. This might motivate future strategies for biomaterial-based tissue regeneration.

[The central nervous system and neuroendocrine system in the regulation of the immune response]. / El sistema nervioso central y el sistema neuroendócrino en la regulación de la respuesta inmune.

There is at present a clear trend in the study of psychoneuroimmunoregulatory events. Different experimental models have demonstrated: a) the participation of stress, psychosocial factors and the central nervous system in the regulation of the immune response; b) an extensive innervation by the autonomic nervous system of the lymphatic organs; c) the presence of receptors for the neuroendocrine mediators in the mononuclear peripheral cells; d) the activity of neuropeptides, hormones and neurotransmitters in lymphocyte activation and function; e) the production of neuroendocrine substances by lymphocytes; f) the existence of feedback pathways in the immune system. In our laboratory we have contributed to these studies with the description of: a) the regulatory activity of different neuroendocrine substances on interferon-gamma production; b) the characterization of the immune regulation exercised by the muscarinic cholinergic system; c) the in vitro activity of the indoleamines, serotonin and melatonin on the immune response, and the production of these indoleamines by lymphocytes and monocytes, thus establishing a model of paracrine regulation.

El sistema nervioso central y el sistema neuroendócrino en la regulación de la respuesta inmune. / [The central nervous system and neuroendocrine system in the regulation of the immune response]

There is at present a clear trend in the study of psychoneuroimmunoregulatory events. Different experimental models have demonstrated: a) the participation of stress, psychosocial factors and the central nervous system in the regulation of the immune response; b) an extensive innervation by the autonomic nervous system of the lymphatic organs; c) the presence of receptors for the neuroendocrine mediators in the mononuclear peripheral cells; d) the activity of neuropeptides, hormones and neurotransmitters in lymphocyte activation and function; e) the production of neuroendocrine substances by lymphocytes; f) the existence of feedback pathways in the immune system. In our laboratory we have contributed to these studies with the description of: a) the regulatory activity of different neuroendocrine substances on interferon-gamma production; b) the characterization of the immune regulation exercised by the muscarinic cholinergic system; c) the in vitro activity of the indoleamines, serotonin and melatonin on the immune response, and the production of these indoleamines by lymphocytes and monocytes, thus establishing a model of paracrine regulation.