Recombinant adenoviral vectors have potential for the treatment of a variety of musculoskeletal defects and such gene therapy systems have been a recent research focus in orthopedic surgery. In studies reported here, two different adenovirus vectors have been compared for their ability to transduce human bone marrow mesenchymal stem cells (hBM-MSCs) and elicit bone formation in vivo. Vectors consisted either of standard adenovirus type 5 (Ad5) vector or a chimeric adenovirus type 5 vector that contains an adenovirus type 35 fiber (Ad5F35), which has been recently demonstrated to bestow a different cellular tropism, and a complete cDNA encoding human bone morphogenetic 2 (BMP2). Studies were also conducted to compare the transduction efficiency of these vectors using enhanced green fluorescent protein (GFP). hBM-MSCs transduced with Ad5F35 vectors had higher levels of transgene expression than those transduced with Ad5 vectors. The results also demonstrate that hBM-MSCs lack the coxsackie-adenovirus receptor (CAR), which is responsible for cellular adsorption of Ad5. Therefore, the data suggest that Ad5 virus adsorption to hBM-MSCs is inefficient. Ad5BMP2- or Ad5F35BMP2-transduced hBM-MSCs were also compared in an in vivo heterotopic bone formation assay. Mineralized bone was radiologically identified only in muscle that received the Ad5F35BMP2 transduced hBM-MSCs. In summary, Ad5F35BMP2 can efficiently transduce hBM-MSCs leading to enhanced bone formation in vivo.

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Intracellular calcium is increased in vulnerable spinal motoneurons in immune-mediated as well as transgenic models of amyotrophic lateral sclerosis (ALS). To determine whether intracellular calcium levels are in¯uenced by the calciumbinding protein parvalbumin, we developed transgenic mice overexpressing parvalbumin in spinal motoneurons. ALS immunoglobulins increased intracellular calcium and spontaneous transmitter release at motoneuron terminals in control animals, but not in parvalbumin overexpressing transgenic mice. Parvalbumin transgenic mice interbred with mutant SOD1 (mSOD1) transgenic mice, an animal model of familial ALS, had signi®cantly reduced motoneuron loss, and had delayed disease onset (17%) and prolonged survival (11%) when compared with mice with only the mSOD1 transgene. These results af®rm the importance of the calcium binding protein parvalbumin in altering calcium homeostasis in motoneurons. The increased motoneuron parvalbumin can signi®-cantly attenuate the immune-mediated increases in calcium and to a lesser extent compensate for the mSOD1-mediated toxic-gain-of-function' in transgenic mice.

Ethanol exposure during development leads to alterations in neuronal differentiation and profound neuronal loss in multiple regions of the developing brain. Although differentiating Purkinje cells of the cerebellum are particularly vulnerable to ethanol exposure, the mechanisms that ameliorate ethanol‐induced Purkinje cell loss have not been well defined. Previous research indicates that glial‐derived neurotrophic factor (GDNF), a member of the transforming growth factor‐β family, promotes the survival of several neuronal populations, including cerebellar Purkinje cells. Therefore, we examined whether GDNF could attenuate ethanol‐induced Purkinje cell loss in an in vitro model system using calbindin‐D28k‐immunoreactivity as a specific marker for Purkinje cells. We found that ethanol led to a significant dose‐related decline in calbindin‐D28k‐immunoreactive cells in explant cultures of the developing cerebellum. However, concurrent administration of GDNF led to a significant rescue of calbindin‐D28k‐immunoreactive cells. Therefore, our results suggest that GDNF prevents ethanol‐associated Purkinje cell loss. © 1997 John Wiley & Sons, Inc. J Neurobiol 33: 835–847, 1997