ESPE Yearbook of Paediatric Endocrinology

To read the full abstract: J Appl Physiol (1985) 2017;123:1101-1109

IGF-1 is a major regulator of growth plate chondrocyte proliferation. While knockout studies reveal substantial impact from both systemic as well from locally-derived IGF-1, transport and distribution patterns within the growth plate remain unknown. Theoretical approaches have been developed to understand the distribution of IGF-1 within the growth plate but have not be proven in vivo thus far. Here, the authors used multiphoton microscopy to track fluorescently labelled IGF-1 take up into growth plate cartilage in vivo for the first time. In contrast to inert molecules, the distribution of IGF-1 followed a very distinct pattern with indication of intracellular localization as early as 30-90 minutes after systemic application. Stunningly, perichondrial tissue exhibited the opposite pattern of efficiently trapping IGF-1 in the matrix, assuming a storage function. Using state-of the art technology, this study provides novel insights into local growth factor trafficking, as well as the role of different tissue compartments. Similar studies on further key regulators of linear growth may shed new light on growth plate regulation and identify new strategies for specific drug delivery.