Neurotrophic effects of vascular endothelial growth factor and neurotrophins on cultured major pelvic ganglia

In a study by researchers from San Francisco and Taiwan, a ganglial culture system is used to screen various growth factors. The aim was to assess these growth factors as possible therapeutic agents for pelvic floors nerve injuries. They found that vascular endothelial growth factor causes a marked neurotrophic effect. Other researchers from Ann Arbor describe a method of immobilising extracellular matrix proteins to potential growth surfaces, and found that this enhances the attachment of cultured cells. They felt that this might lead to the development of other methods of tissue engineering. The authors from Japan describe a study wherein they investigated whether prenatal stress affected the pituitary‐testicular axis and thus testicular descent in rat fetuses; they report that this may indeed be the mechanism. OBJECTIVE To investigate the feasibility of using a ganglial culture system to screen various growth factors as potential therapeutic agents for pelvic nerve injuries. MATERIALS AND METHODS The major pelvic ganglia (MPG) were isolated from male rats and attached to culture dishes with the aid of MatrigelTM (Becton Dickinson, Mountain View, CA, USA). Alternatively, the dorso‐caudal region (DCR) of MPG, from which the cavernous nerves originate, was dissected and then attached to a Matrigel‐coated coverslip. The MPG or DCR was cultured in serum‐free medium supplemented with phosphate‐buffered saline (PBS, control), 50 ng/mL of vascular endothelial growth factor (VEGF), 20 ng/mL of a neurotrophin (BDNF, NT3, or NT4), or combinations of these growth factors. After 2 days of incubation, the ganglial tissues with their outgrowing nerve fibres were stained for the expression of NADPH‐diaphorase, tyrosine hydroxylase (TH) and acetylcholinesterase (AChE). The length and staining intensity of nerve fibres were analysed. RESULTS The outgrowing fibres were significantly longer in MPG treated with any of the four tested growth factors than in PBS‐treated MPG. The combination of VEGF and NT3 induced the best fibre growth. Improvements to the culturing conditions allowed a histological examination of the outgrowing fibres for the expression of nitric oxide synthase (NOS), TH and AChE. VEGF and BDNF were equally capable of inducing NOS‐ and TH‐expressing fibres. BDNF was much weaker than VEGF for inducing AChE‐expressing fibres. CONCLUSIONS This improved culturing system is potentially useful for screening nerve‐regenerating factors; VEGF had neurotrophic effects