Abstract
Background aims. Mucopolysaccharidosis type I (MPS I) is characterized by deficiency of the enzyme alpha-l-iduronidase (IDUA) and storage of glycosaminoglycans (GAG) in several tissues. Current available treatments present limitations, thus the search for new therapies. Encapsulation of recombinant cells within polymeric structures combines gene and cell therapy and is a promising approach for treating MPS I. Methods. We produced alginate microcapsules containing baby hamster kidney (BHK) cells overexpressing IDUA and implanted these capsules in the peritoneum of MPS I mice. Results. An increase in serum and tissue IDUA activity was observed at early time-points, as well as a reduction in GAG storage; however, correction in the long term was only partially achieved, with a drop in the IDUA activity being observed a few weeks after the implant. Analysis of the capsules obtained from the peritoneum revealed inflammation and a pericapsular fibrotic process, which could be responsible for the reduction in IDUA levels observed in the long term. In addition, treated mice developed antibodies against the enzyme. Conclusions. The results suggest that the encapsulation process is effective in the short term but improvements must be achieved in order to reduce the immune response and reach a stable correction.
Acknowledgments
We would like to thank Elisabeth Neufeld (UCLA, USA) for the generous gift of MPS I mice, and Dr Nance Nardi and Dr Melissa Camassola (ULBRA, Brazil) for providing the pR-IDUA vector. This work was supported by grants from Conselho Nacional de Desenvolvimento Cientifico-CNPq and Fundo de Incentivo a Pesquisa do Hospital de Clinicas de Porto Alegre (FIPE-HCPA).
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.