Extended Data Fig. 1: Experimental models and timelines. | Nature

Extended Data Fig. 1: Experimental models and timelines.

From: Required growth facilitators propel axon regeneration across complete spinal cord injury

Extended Data Fig. 1

Mice or rats received different combinations of procedures including adeno-associated virus (AAV) injections, complete crush SCI, injections of one or two depots of hydrogel containing different molecular cargoes and injections of biotinylated dextran amine (BDA) for axonal tract-tracing. AAV injections were made two weeks before SCI to allow time for molecular expression and were targeted at propriospinal neurons (PrSp) between one and two segments rostral to planned locations of SCI lesions. AAVs were used to deliver either potential axon-growth reactivating molecules, GFP to identify targeted neurons or RFP as an axonal tract-tracer. Complete crush SCI lesions were placed at the level of spinal segment T10. Two days after SCI, all animals were behaviourally evaluated for completeness of SCI and only animals with functionally complete SCI were included in subsequent experimental steps. Additional animals with complete SCI were evaluated without hydrogel injections (SCI only). a, Schematic and timeline of one-depot experiments. Two days after complete crush SCI, animals received hydrogel injections targeted to the centre of the non-neural lesion core. These depots (D1) contained different molecular cargos as listed in the schematic. Depots without cargo were referred to as ‘empty’. b, Schematic and timeline of two-depot experiments. Two days after complete crush SCI, animals received a D1 hydrogel injection into the centre of the non-neural lesion core to deliver the growth factors FGF + EGF + GDNF. Nine days after SCI, the animals received a second hydrogel injection (D2) targeted to spared neural tissue 1 to 2 mm caudal to the lesion centre to deliver GDNF to sequentially chemoattract propriospinal axons that had regrown into the lesion core. BDA injections for axonal tract-tracing were targeted at propriospinal neurons between one and two segments rostral to SCI lesions and were placed at the time of injecting either D1 (a) or D2 (b). Tissue was collected for evaluation at either two or four weeks after SCI. Electrophysiological evaluations were conducted at four weeks after SCI. For abbreviations, see Extended Data Table 1.