Sustained delivery of thermostabilized chABC enhances axonal sprouting and functional recovery after spinal cord injury
Sustained delivery of thermostabilized chABC enhances axonal sprouting and functional recovery after spinal cord injury
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DOI：
10.1073/pnas.0905437106
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发表时间：
2010-02-23
影响因子：
11.1
通讯作者：
Bellamkonda, Ravi V.
中科院分区：
文献类型：
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作者：
Lee, Hyunjung;McKeon, Robert J.;Bellamkonda, Ravi V.
硫酸软骨素蛋白多糖(CSPGs)是一类主要的轴突生长抑制物，在脊髓损伤(SCI)后表达上调，并导致再生失败。软骨素酶ABC(ChABC)能消化CSPG上的糖胺多聚糖链，从而克服CSPG介导的抑制作用。但chABC在37摄氏度时会迅速失去酶活性，需要重复注射或局部输注数天至数周。这些输液系统具有侵入性，容易感染，在临床上存在问题。为了克服这一限制，我们已经对chABC进行了热稳定，并开发了一种在体内持续局部给药的系统，消除了对长期植入的导管和泵的需要。热稳定的chABC在体外37℃下保持活性长达4周。当热稳定的chABC通过水凝胶-微管支架系统输送时，CSPG在体内的水平一直很低，直到脊髓损伤后6周。持续局部释放热稳定的chABC与单一治疗未稳定的chABC相比，轴突生长和功能恢复在CSPG消化方面显示出显著差异。热稳定的chABC联合持续神经营养因子-3治疗的动物，运动功能显著改善，促进霍乱毒素B亚单位阳性感觉神经轴突的生长和5-羟色胺能纤维的萌发。因此，提高chABC的热稳定性有助于微创、持续、局部传递chABC，这在克服CSPG介导的再生失败方面具有潜在的有效作用。热稳定的chABC与神经营养因子联合治疗可促进脊髓损伤后轴突的再生、萌发和功能恢复。
Chondroitin sulfate proteoglycans (CSPGs) are a major class of axon growth inhibitors that are up-regulated after spinal cord injury (SCI) and contribute to regenerative failure. Chondroitinase ABC (chABC) digests glycosaminoglycan chains on CSPGs and can thereby overcome CSPG-mediated inhibition. But chABC loses its enzymatic activity rapidly at 37 degrees C, necessitating the use of repeated injections or local infusions for a period of days to weeks. These infusion systems are invasive, infection-prone, and clinically problematic. To overcome this limitation, we have thermostabilized chABC and developed a system for its sustained local delivery in vivo, obviating the need for chronically implanted catheters and pumps. Thermostabilized chABC remained active at 37 degrees C in vitro for up to 4 weeks. CSPG levels remained low in vivo up to 6 weeks post-SCI when thermostabilized chABC was delivered by a hydrogel-microtube scaffold system. Axonal growth and functional recovery following the sustained local release of thermostabilized chABC versus a single treatment of unstabilized chABC demonstrated significant differences in CSPG digestion. Animals treated with thermostabilized chABC in combination with sustained neurotrophin-3 delivery showed significant improvement in locomotor function and enhanced growth of cholera toxin B subunit-positive sensory axons and sprouting of serotonergic fibers. Therefore, improving chABC thermostability facilitates minimally invasive, sustained, local delivery of chABC that is potentially effective in overcoming CSPG-mediated regenerative failure. Combination therapy with thermostabilized chABC with neurotrophic factors enhances axonal regrowth, sprouting, and functional recovery after SCI.