Julio Manuel Rios de la Rosa
University of Manchester
Julio obtained his BSc/MSc in Biotechnology at Universidad Pablo de Olavide, Spain in 2013. During his studies he conducted research in Seville and Barcelona supported by highly competitive grants, such as JAE-Intro (CSIC). In September 2013 he joined the University of Manchester as part of the NoWNANO DTC. Julio recently completed his PhD thesis on 'Hyaluronic acid vehicles for cell targeting' and is currently a Research Associate at the North West Centre for Advanced Drug Delivery (NoWCADD), a translational centre based at the University of Manchester funded through AstraZeneca. His research focuses on the characterisation of colloidal and macromolecular carriers.
Introduction: CD44 is the major receptor of hyaluronic acid (HA) on cell membranes, where it fulfils anchoring, signalling and endocytic functions. This multi-faceted role renders CD44 a key mediator in cellular responses... [ view full abstract ]
Introduction: CD44 is the major receptor of hyaluronic acid (HA) on cell membranes, where it fulfils anchoring, signalling and endocytic functions. This multi-faceted role renders CD44 a key mediator in cellular responses to their microenvironment both in homeostasis and pathological processes. In particular, the (over)expression of CD44 variant isoforms (CD44v) in solid tumours has attracted interest in the design of HA-based targeting therapies. However, the caveats of such strategies are a poor understanding of the target itself (in terms of HA interactions) and its ubiquitous expression in healthy tissue.
Methods: In order to predict the targeting behaviour of HA already in vitro, we have first evaluated the expression of CD44 in relevant cancer and normal human cell lines (via flow cytometry) and then cross-correlated it with: the uptake kinetics of fluorescently-labeled HA-exposing chitosan nanoparticles on cell lysates or live cells, respectively discriminating between overall uptake and internalisation, and the functional delivery of siRNA, examined by RT-PCR.
Results: We found a high CD44 expression in colorectal cancer cell lines and a moderate-to-high expression in pancreatic ones, the latter comparable to that of fibroblasts and endothelial cells. Macrophages expressed polarisation-dependent low levels of CD44. As expected, the distinct expression pattern in cancer and normal cells was reflected in a different nanoparticle uptake, hence in their overall silencing efficiency. In most cases the relationship between CD44 expression and targetability of HA-exposing nanoparticles was straightforward; for instance, CD44-overexpressing HCT-116 cells showed a significantly higher nanoparticle internalisation compared to normal cells and achieved >70% knockdown. However, we found an inverse correlation between nanoparticle internalisation and CD44 expression for some cell lines (e.g. THP-1 M1, HT-29).
Discussion: Despite the preferential uptake of HA-exposing nanoparticles by cancer cells, the relationship between CD44 expression and HA internalisation is not always as simplistic as ‘higher CD44 = better targetability’. Paradoxically, our results suggest that cells expressing high levels of CD44, and potentially best HA binders, may turn out to be the most difficult to treat because of the slower/more difficult internalization of HA-based materials.
