Release and pharmacokinetics of near-infrared labeled albumin from monodisperse poly(d,l-lactic-co-hydroxymethyl glycolic acid) microspheres after subcapsular renal injection.

Subcapsular renal injection is a novel administration method for local delivery of therapeutics for the treatment of kidney related diseases. The aim of this study was to investigate the feasibility of polymeric microspheres for sustained release of protein therapeutics in the kidney and study the subsequent redistribution of the released protein. For this purpose, monodisperse poly(d,l-lactic-co-hydroxymethyl glycolic acid) (PLHMGA) microspheres (40 µm in diameter) loaded with near-infrared dye-labeled bovine serum albumin (NIR-BSA) were prepared by a membrane emulsification method. Rats were injected with either free NIR-BSA or with NIR-BSA loaded microspheres (NIR-BSA-ms) and the pharmacokinetics of the released NIR-BSA was studied for 3 weeks by ex vivo imaging of organs and blood. Quantitative release data were obtained from kidney homogenates and possible metabolism of the protein was investigated by SDS-PAGE analysis of the samples. The ex vivo images showed a rapid decrease of the NIR signal within 24h in kidneys injected with free NIR-BSA, while, importantly, the signal of the labeled protein was still visible at day 21 in kidneys injected with NIR-BSA-ms. SDS-PAGE analysis of the kidney homogenates showed that intact NIR-BSA was released from the microspheres. The locally released NIR-BSA drained to the systemic circulation and subsequently accumulated in the liver, where it was degraded and excreted renally. The in vivo release of NIR-BSA was calculated after extracting the protein from the remaining microspheres in kidney homogenates. The in vivo release rate was faster (89 ± 4% of the loading in 2 weeks) compared to the in vitro release of NIR-BSA (38 ± 1% in 2 weeks). In conclusion, PLHMGA microspheres injected under the kidney capsule provide a local depot from which a formulated protein is released over a prolonged time-period.

Effective treatment of experimental lupus nephritis by combined administration of anti-CD11a and anti-CD54 antibodies.

Mice with chronic graft-versus-host disease (GVHD), induced by injection of DBA/2 lymphocytes in (C57BL10*DBA/2) F1 hybrids, develop a syndrome resembling systemic lupus erythematosus (SLE) with immune complex glomerulonephritis. In this model we evaluated the role of interactions between CD11a (LFA-1alpha) and CD54 (intercellular adhesion molecule-1 (ICAM-1)) molecules on leucocytes in the development of renal disease in systemic autoimmunity. Two weeks after induction of GVHD, when anti-nuclear autoantibodies were detected in the circulation and immune complexes had formed in the glomeruli, mice were injected twice per week with rat anti-CD11a and anti-CD54 MoAbs, or with their vehicle PBS, or with control rat IgG. MoAb treatment significantly lowered albuminuria and increased survival compared with control mice with GVHD. In the glomeruli of MoAb-treated mice there was markedly less binding of immunoglobulin and C3, while anti-renal tubular epithelium autoantibodies, but not anti-glomerular basement membrane autoantibodies, were significantly lowered in the circulation 4 weeks after disease induction. In addition, MoAb treatment inhibited the glomerular influx of CD11a+ cells and decreased development of histological abnormalities in the kidneys. Both rat IgG- and MoAb-treated mice developed anti-rat immunoglobulin antibodies. Furthermore, a marked splenomegaly with an increase of the T cell compartment was observed in MoAb-treated mice with GVHD. These results show that CD11a/CD54 interactions are crucial for the full-blown development of lupus nephritis in this model. Treatment aimed at blocking the activity of these molecules profoundly attenuated the development of renal disease in chronic GVHD even if started when first symptoms of SLE (i.e. anti-nuclear autoantibodies in sera and glomerular binding of immunoglobulins) were already detectable.