To mimic the extracellular matrix surrounding high grade gliomas, composite matrices composed of either acid-solubilized (AS) or pepsin-treated (PT) collagen and the glycosaminoglycans chondroitin sulfate (CS) and hyaluronic acid (HA) are prepared and characterized. The structure and mechanical properties of collagen/CS and collagen/HA gels are studied via confocal reflectance microscopy (CRM) and rheology. CRM reveals that CS induces fibril bundling and increased mesh size in AS collagen but not PT collagen networks. The presence of CS also induces more substantial changes in the storage and loss moduli of AS gels than of PT gels, in accordance with expectation based on network structural parameters. The presence of HA significantly reduces mesh size in AS collagen but has a smaller effect on PT collagen networks. However, both AS and PT collagen network viscoelasticity is strongly affected by the presence of HA. The effects of CS and HA on glioma invasion is then studied in collagen/GAG matrices with network structure both similar to (PT collagen-based gels) and disparate from (AS collagen-based gels) those of the corresponding pure collagen matrices. It is shown that CS inhibits and HA has no significant effect on glioma invasion in 1.0 mg/ml collagen matrices over 3 days. The inhibitory effect of CS on glioma invasion is more apparent in AS than in PT collagen gels, suggesting invasive behavior in these environments is affected by both biochemical and network morphological changes induced by GAGs. This study is among the few efforts to differentiate structural, mechanical and biochemical effects of changes to matrix composition on cell motility in 3D.

While mast cells in connective tissues have long been associated with allergic reactions, it is now clear that they are also present within the central nervous system under normal physiological conditions. The mast cell population increases 10-fold in the medial habenular region of the brain within 2 h after pairing in doves. The first study explored whether this increase was due to exposure to gonadal steroids. Light microscopic immunocytochemistry indicates an increased number of brain MC following exposure to either testosterone (T) or dihydrotestosterone (DHT) in the male, or 17beta estradiol (E) in the female, but not in cholesterol-treated controls. Thus, the increased habenular MC population is produced by gonadal hormones in the absence of sexual behavior, is not sexually dimorphic, and does not require aromatization of androgen. In the next study, MC activational state was determined using electron microscopy. Cells were categorized into five states: (I) resting; (II) initiation of degranulation; (III) fully degranulated; (IV) piecemeal secretion; and (V) resynthesizing. Hormone treatment (T, DHT, or E) resulted in a significant increase in the percent of cells in activated states. MC granules contain a wide range of biologically active molecules. The release of these granule contents into the neuropil of the central nervous system is likely to have wide ranging effects at multiple levels including vascular permeability and neuronal excitability. In that steroid treatment is known to result in such effects, the present demonstration of a hormonally induced shift in MC secretory state is one avenue by which these effects are mediated.