Prenatal LPS increases inflammation in the substantia nigra of Gdnf heterozygous mice

Prenatal systemic inflammation has been implicated in neurological diseases, but optimal animal models have not been developed. We investigated whether a partial genetic deletion of glial cell line-derived neurotrophic factor (Gdnf(+/-)) increased vulnerability of dopamine (DA) neurons to prenatal lipopolysaccharide (LPS). LPS [0.01 mg/kg intraperitoneal (i.p.)] or saline was administered to wild-type (WT) or Gdnf(+/-) pregnant mice on gestational day 9.5. Male offspring were examined at 3 weeks, 3 and 12 months of age. There was a progressive degeneration of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra (SN) with age in Gdnf(+/-) but not in WT mice, with no observed effects on locus coeruleus (LC) noradrenergic neurons or DA neurons of the ventral tegmental area. Inflammatory markers were elevated in SN of LPS treated offspring, with exacerbation in Gdnf(+/-) mice. Intracellular accumulation of α-synuclein (α-syn) immunoreactivity in DA neurons of SN was observed in all groups of Gdnf(+/-) and in WT mice with prenatal LPS, with altered distribution between pars reticulata (pr) and pars compacta (pc). The findings suggest that prenatal LPS leads to accelerated neuropathology in the SN with age, and that a partial loss of GDNF exacerbates these effects, providing a novel model for age-related neuropathology of the nigrostriatal DA system.

Role of solvent/non-solvent ratio on microsphere formation using the solvent removal method

The importance of good solvent concentration in the non-solvent mixture and the non-solvent viscosity on the ability to form microspheres using solvent removal process was investigated. The higher the viscosity of the polymer solutions, the higher the concentration of good solvent needed in the nonsolvent mixture to produce microspheres. This finding was due to faster precipitation of the polymer phase. Also, the addition of a model drug, fluorescein isothiocyanate conjugated-labelled bovine serum albumin, to the polymer solution (10% poly-L-lactic acid:poly(fumaric-co-sebacic) anhydride in methylene chloride) resulted in an overall lower polymer solution viscosity (15.5 cP with fluorescein isothiocyanate conjugated-labelled bovine serum albumin as compared with 18.25 cP for blank polymer at 25 degrees C). Additionally, the effect of good solvent concentration on non-solvent viscosity was evaluated, and the viscosity decreased as the concentration of good solvent increased. The effect of good solvent concentration on the non-solvent mixture on sphere formation was of great importance. Microspheres would not form when the good polymer solvent (methylene chloride) in the non-solvent phase was too low (below 175 ml for poly-L-lactic acid or 150 ml for poly(D,L-lactidco-glycolid)) or was replaced by another good solvent such as ethyl acetate, even though the same viscosity was achieved. It was shown that the concentration of the good solvent in the non-solvent mixture was more of a controlling factor than the viscosity of the non-solvent mixture in microsphere formation and the findings support the conclusion that diffusion is the main controlling parameter in solvent removal.

Degradation of multi-phase microspheres fabricated via solvent removal

Multi-phase polymer microspheres for drug encapsulation have been fabricated via solvent removal using poly(-lactic) acid (PLLA) and poly(fumaric-co-sebacic) anhydride (20:80) (P(FA:SA) (20:80)). The process by which these spheres degrade was investigated. Characterization was conducted to determine the extent of degradation of the two polymer phases over 16 weeks using scanning-electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), gel-permeation chromatography (GPC), differential-scanning calorimetry (DSC) and nuclear magnetic resonance (NMR). These experiments showed that the P(FA:SA) (20:80) phase of the multi-phase microspheres degraded faster than the PLLA phase, leaving only some of the poly(sebacic) oligomers after 16 weeks in both the in vitro and in vivo studies. These portions could remain because they were entrapped in the PLLA phase, preventing more rapid degradation. The PLLA phase showed minimal changes over the 16 week period; there was no significant change in crystallinity and only a small decrease in molecular weight in both the in vitro and in vivo studies. The in vitro study showed a rapid mass loss initially (first 3 days), followed by a fairly constant mass through 16 weeks, while the in vivo study showed a mass gain due to tissue influx.

The effects of infiltration on protein release from multi-phase microspheres fabricated via solvent removal

Multi-phase polymer microspheres for drug encapsulation have been fabricated via solvent removal using poly(L-lactic) acid (PLLA) and poly(fumaric-co-sebacic) anhydride (P(FA:SA)20:80). A process of protein infiltration by the polymer solution was studied to determine the effect on protein release. Additionally, multiple variations of the infiltration process were investigated. The mechanisms involved in the different infiltration methods were looked at to determine if polymer degradation was occurring or if the protein was aggregating as a result of the infiltration process. Multiple drugs were used in these studies: FITC-labelled bovine serum albumin (BSA), a model drug and antide (a GnRH antagonist), which is a therapeutic agent. Characterization and comparison of the various microsphere batches was performed via scanning-electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), gel-permeation chromatography (GPC) and differential-scanning calorimetry (DSC). Protein infiltration by the polymer solution was successful in decreasing the initial burst of drug with insignificant differences between the various methods of infiltration. Furthermore, there were minimal differences in polymer degradation due to the different methods of infiltration and there were no significant differences in the degree of crystallinity of the polymers in the various batches fabricated with and without infiltration.