Hindlimb heating increases vascular access of large molecules to murine tibial growth plates measured by in vivo multiphoton imaging
Hindlimb heating increases vascular access of large molecules to murine tibial growth plates measured by in vivo multiphoton imaging
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DOI：
10.1152/japplphysiol.01212.2013
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发表时间：
2014-02-01
影响因子：
3.3
通讯作者：
Williams, Rebecca M.
中科院分区：
文献类型：
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作者：
Serrat, Maria A.;Efaw, Morgan L.;Williams, Rebecca M.
在理解纵向生长的分子调控方面的进展导致了针对生长板疾病的新的药物治疗的发展。尽管取得了进展，但一个尚未满足的主要挑战是将治疗剂输送到无血管软骨板上。致密的细胞外基质和缺乏穿透血管形成了半透“屏障”，阻碍了血管-软骨界面的分子运输。为了克服这一障碍，我们使用后肢加热模型来操纵5周龄雌性小鼠(n=22)的骨循环。温度代表了正常人类膝关节的生理范围。我们使用体内多光子显微镜来量化温度增强的大分子进入胫骨生长板的输送。我们测试了这样的假设，即将后肢温度从22摄氏度提高到34摄氏度会增加大系统分子的血管通路，使用10、40和70 kDa的右旋糖苷进行建模，这三种右旋糖苷的大小与生理调节因子的大小大致相同。血管通路通过血管直径、流速、软骨膜下神经丛血管中的葡聚糖渗漏和生长板软骨中的堆积来量化。在34℃时，10 kDa右旋糖苷进入生长板增加了150%，40 kDa和70 kDa右旋糖苷进入生长板增加了50%，这表明温度增加是大小依赖的。神经丛中的总葡聚糖水平在34摄氏度时增加，但血管外的相对渗漏不依赖于温度。在34℃时，血流速度和血管直径分别增加了118%和31%。这些结果表明，热增强了生长板周围的血管承载能力和大分子的生物利用度，表明温度可能是一种非侵入性策略，用于调节治疗药物向受损儿童生长板的输送。
Advances in understanding the molecular regulation of longitudinal growth have led to development of novel drug therapies for growth plate disorders. Despite progress, a major unmet challenge is delivering therapeutic agents to avascular-cartilage plates. Dense extracellular matrix and lack of penetrating blood vessels create a semipermeable "barrier," which hinders molecular transport at the vascular-cartilage interface. To overcome this obstacle, we used a hindlimb heating model to manipulate bone circulation in 5-wk-old female mice (n = 22). Temperatures represented a physiological range of normal human knee joints. We used in vivo multiphoton microscopy to quantify temperature-enhanced delivery of large molecules into tibial growth plates. We tested the hypothesis that increasing hindlimb temperature from 22 degrees C to 34 degrees C increases vascular access of large systemic molecules, modeled using 10, 40, and 70 kDa dextrans that approximate sizes of physiological regulators. Vascular access was quantified by vessel diameter, velocity, and dextran leakage from subperichondrial plexus vessels and accumulation in growth plate cartilage. Growth plate entry of 10 kDa dextrans increased > 150% at 34 degrees C. Entry of 40 and 70 kDa dextrans increased < 50%, suggesting a sizedependent temperature enhancement. Total dextran levels in the plexus increased at 34 degrees C, but relative leakage out of vessels was not temperature dependent. Blood velocity and vessel diameter increased 118% and 31%, respectively, at 34 degrees C. These results demonstrate that heat enhances vascular carrying capacity and bioavailability of large molecules around growth plates, suggesting that temperature could be a noninvasive strategy for modulating delivery of therapeutics to impaired growth plates of children.