RESUMEN
Hypophosphatemic rickets is caused by renal phosphate wasting that is most commonly due to X-linked dominant mutations in PHEX. PHEX mutations cause hypophosphatemia indirectly, through the increased expression of fibroblast growth factor 23 (FGF23) by osteocytes. FGF23 decreases renal phosphate reabsorption and thereby increases phosphate excretion. The lack of phosphate leads to a mineralization defect at the level of growth plates (rickets), bone tissue (osteomalacia), and teeth, where the defect facilitates the formation of abscesses. The bone tissue immediately adjacent to osteocytes often remains unmineralized ("periosteocytic lesions"), highlighting the osteocyte defect in this disorder. Common clinical features of XLH include deformities of the lower extremities, short stature, enthesopathies, dental abscesses, as well as skull abnormalities such as craniosynostosis and Chiari I malformation. For the past four decades, XLH has been treated by oral phosphate supplementation and calcitriol, which improves rickets and osteomalacia and the dental manifestations, but often does not resolve all aspects of the mineralization defects. A newer treatment approach using inactivating FGF23 antibodies leads to more stable control of serum inorganic phosphorus levels and seems to heal rickets more reliably. However, the long-term benefits of FGF23 antibody treatment remain to be elucidated.
Asunto(s)
Raquitismo Hipofosfatémico Familiar/patología , Factores de Crecimiento de Fibroblastos/metabolismo , Osteomalacia/patología , Endopeptidasa Neutra Reguladora de Fosfato PHEX/genética , Fosfatos/metabolismo , Absorciometría de Fotón , Desarrollo Óseo/efectos de los fármacos , Desarrollo Óseo/genética , Huesos/diagnóstico por imagen , Huesos/patología , Calcificación Fisiológica/efectos de los fármacos , Calcificación Fisiológica/genética , Calcitriol/administración & dosificación , Raquitismo Hipofosfatémico Familiar/diagnóstico , Raquitismo Hipofosfatémico Familiar/tratamiento farmacológico , Raquitismo Hipofosfatémico Familiar/genética , Factor-23 de Crecimiento de Fibroblastos , Factores de Crecimiento de Fibroblastos/antagonistas & inhibidores , Humanos , Osteocitos/metabolismo , Osteomalacia/diagnóstico , Osteomalacia/tratamiento farmacológico , Osteomalacia/genética , Endopeptidasa Neutra Reguladora de Fosfato PHEX/metabolismo , Comunicación Paracrina/genética , Fosfatos/administración & dosificación , Fosfatos/sangre , Reabsorción Renal/efectos de los fármacos , Reabsorción Renal/genética , Diente/crecimiento & desarrollo , Diente/patología , Resultado del TratamientoRESUMEN
Finding the appropriate cues to trigger the desired differentiation is a challenge in tissue engineering when stem cells are involved. In this regard, three-dimensional environments are often compared to cells' two-dimensional culture behaviour (plastic culture dish). Here, we compared the gene expression pattern of human adipose-derived stem cells (ASC) seeded in a three-dimensional (3D) electrospun mesh and on a two-dimensional (2D) film - both of exactly the same material. Additionally, we conducted experiments with a scaffold floating above a film to investigate two-way paracrine effects (co-system). Electrospun meshes (3D scaffolds) and films (2D), consisting either of pristine poly-lactic-co-glycolic acid (PLGA) or of PLGA-containing dispersed amorphous calcium phosphate nanoparticles (PLGA/aCaP), were seeded with ASCs and cultured either in Dulbecco Minimum Essential Medium (DMEM) or in osteogenic medium. After two weeks, minimum stem cell criteria markers as well as typical markers for osteogenesis, endothelial cell differentiation, adipogenesis and chondrogenesis were analysed by quantitative real-time PCR. Interestingly, mostly osteogenic genes of cells seeded on 3D meshes were upregulated compared to those on 2D films, while stem cell markers seemed to be only slightly affected. Runx2 and osteocalcin showed an especially strong upregulation under all conditions, while most other factors analysed for 2D/3D changes were highly dependent on the material composition, the culture medium and on paracrine signalling effects. The beneficial 3D environment for stem cells found in many studies has therefore not to be attributed to the third dimension alone and should carefully be compared to 2D films fabricated of the same material. Furthermore, paracrine interactions triggering differentiation are not negligible.
Asunto(s)
Tejido Adiposo/citología , Perfilación de la Expresión Génica/métodos , Células Madre/citología , Células Madre/metabolismo , Adipogénesis/genética , Técnicas de Cultivo de Célula/métodos , Diferenciación Celular/genética , Células Cultivadas , Condrogénesis/genética , Técnicas de Cocultivo , Humanos , Comunicación Paracrina/genética , Poliésteres/química , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Ingeniería de Tejidos/métodos , Andamios del Tejido/químicaRESUMEN
OBJECTIVE: The aim of this study is to investigate the temporal and spatial expression and localization of transforming growth factor-beta 1 mRNA during mouse tooth development. METHODS: The distribution pattern of TGF-beta 1 mRNA during tooth development was analyzed on 5 microns serial sections of paraformaldehyde-fixed and paraffin-embedded embryonic mouse heads or mandibles. RESULTS: The results show that TGF-beta 1 mRNA is expressed during mouse tooth development in a temporally and spatially regulated fashion. Local expression of TGF-beta 1 mRNA in the dental epithelium at budstaged (E13) and capstaged (E15) teeth were observed. During bell stage (E16-18), TGF beta 1 mRNA was very abundant in the ameloblast layer and dental papilla cells. The expression of TGF-beta 1 increased in the layer of odontoblast and ameloblast with the differentiation of these cells. CONCLUSION: These results suggest that TGF-beta 1 may have an important role in odontogenesis and that it acts as a paracrine and autoinducing factor.