BioMEMS Resource Center, Center for Engineering in Medicine, Massachusetts General Hospital, Shriners Hospital for Children and Harvard Medical School, Boston, MA 02114, USA.
Lab Chip. 2011 Oct 21;11(20):3530-7. doi: 10.1039/c1lc20377k. Epub 2011 Sep 1.
Oocyte cryopreservation has become an essential tool in the treatment of infertility by preserving oocytes for women undergoing chemotherapy. However, despite recent advances, pregnancy rates from all cryopreserved oocytes remain low. The inevitable use of the cryoprotectants (CPAs) during preservation affects the viability of the preserved oocytes and pregnancy rates either through CPA toxicity or osmotic injury. Current protocols attempt to reduce CPA toxicity by minimizing CPA concentrations, or by minimizing the volume changes via the step-wise addition of CPAs to the cells. Although the step-wise addition decreases osmotic shock to oocytes, it unfortunately increases toxic injuries due to the long exposure times to CPAs. To address limitations of current protocols and to rationally design protocols that minimize the exposure to CPAs, we developed a microfluidic device for the quantitative measurements of oocyte volume during various CPA loading protocols. We spatially secured a single oocyte on the microfluidic device, created precisely controlled continuous CPA profiles (step-wise, linear and complex) for the addition of CPAs to the oocyte and measured the oocyte volumetric response to each profile. With both linear and complex profiles, we were able to load 1.5 M propanediol to oocytes in less than 15 min and with a volumetric change of less than 10%. Thus, we believe this single oocyte analysis technology will eventually help future advances in assisted reproductive technologies and fertility preservation.
卵母细胞冷冻保存已成为治疗化疗女性不孕的重要手段。然而，尽管最近取得了进展，但所有冷冻保存的卵母细胞的妊娠率仍然很低。在保存过程中不可避免地使用冷冻保护剂（CPAs），这会通过 CPA 毒性或渗透损伤影响保存卵母细胞的活力和妊娠率。目前的方案试图通过最小化 CPA 浓度来降低 CPA 毒性，或者通过逐步向细胞中添加 CPAs 来最小化体积变化。尽管逐步添加会降低卵母细胞的渗透压冲击，但由于长时间暴露于 CPAs 中，不幸的是会增加毒性损伤。为了解决当前方案的局限性，并合理设计最大限度减少 CPA 暴露的方案，我们开发了一种微流控装置，用于在各种 CPA 加载方案中定量测量卵母细胞体积。我们在微流控装置上空间固定单个卵母细胞，为卵母细胞添加 CPA 时创建精确控制的连续 CPA 曲线（逐步、线性和复杂），并测量卵母细胞对每个曲线的体积响应。对于线性和复杂曲线，我们能够在不到 15 分钟的时间内将 1.5 M 丙二醇加载到卵母细胞中，体积变化小于 10%。因此，我们相信这种单个卵母细胞分析技术最终将有助于辅助生殖技术和生育力保存的未来发展。
