William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
Transfusion. 2012 Aug;52(8):1729-40. doi: 10.1111/j.1537-2995.2011.03523.x. Epub 2012 Feb 5.
The hemoglobin of the earthworm Lumbricus terrestris (also known as erythrocruorin, or LtEc) is a naturally occurring high-molecular-weight protein assembly (3.6 MDa) that is extremely stable, resistant to oxidation, and transports oxygen similarly to human whole blood. Therefore, LtEc may serve as an alternative to donated human red blood cells. However, a suitable purification process must be developed to produce highly pure LtEc on a large scale that can be evaluated in an animal model to determine the safety and efficacy of LtEc.
We used tangential-flow filtration (TFF), an easily scalable and affordable technique, to produce highly pure LtEc from earthworms. The purity, yield, methemoglobin level, viscosity, colloid osmotic pressure, O(2) binding equilibria, and ligand-binding kinetics of the purified LtEc were measured in vitro. The purified LtEc product was then evaluated in hamsters using a hypervolemic infusion model to establish its basic biocompatibility and detect any changes in microcirculatory and systemic variables.
TFF was able to produce LtEc with high purity and yield (5-10 g/1000 worms). The purified LtEc product did not elicit hypertension or vasoconstriction when infused into hamsters.
LtEc may be easily purified and safely transfused into hamsters in small amounts (0.5-1.5 g/dL final concentration in blood) without any noticeable side effects. Therefore, LtEc may serve as a very promising oxygen carrier for use in transfusion medicine.
蚯蚓（也称为血晶蛋白或 LtEc）的血红蛋白是一种天然存在的高分子量蛋白质组装体（3.6 MDa），具有极高的稳定性、抗氧化性，并且类似人体全血一样运输氧气。因此，LtEc 可能是替代捐献的人类红细胞的一种选择。然而，必须开发出合适的纯化工艺，才能大规模生产高度纯净的 LtEc，并在动物模型中进行评估，以确定 LtEc 的安全性和有效性。
我们使用切向流过滤（TFF），这是一种易于扩展且经济实惠的技术，从蚯蚓中生产高度纯净的 LtEc。在体外测量了纯化的 LtEc 的纯度、产率、高铁血红蛋白水平、粘度、胶体渗透压、O2 结合平衡和配体结合动力学。然后，我们使用高容量输注模型在仓鼠中评估纯化的 LtEc 产品，以确定其基本的生物相容性，并检测微循环和全身变量的任何变化。
TFF 能够生产出高纯度和高产量的 LtEc（每 1000 条蚯蚓产 5-10 克）。纯化的 LtEc 产品输注到仓鼠体内时不会引起高血压或血管收缩。
LtEc 可以很容易地纯化，并以小剂量（血液中最终浓度为 0.5-1.5 g/dL）安全输注到仓鼠体内，没有任何明显的副作用。因此，LtEc 可能是一种非常有前途的氧载体，可用于输血医学。
