利用人类胚胎干细胞用于治疗用途的关键之一是理解帮助干细胞增殖和分化成其他类型细胞的分子信号。如果商业培养基中的化学物质是私有的（这在科研环境中很常见），这项任务就变得更具挑战性。
目前，科学家可能不知道一个培养基中究竟有什么化合物，这导致了无法预测的生长行为，也导致了无法回答哪种成分可能刺激干细胞。Peter Andrews及其同事报告说他们开发了一种含有肝素的干细胞培养基，肝素是一种被美国食品和药品管理局批准使用的广为人知的抗凝血剂。迄今为止，所有报告的干细胞培养基都含有成纤维细胞生长因子2（FGF-2）和一些实验室定制的营养物质的混合。
这种新开发的培养基将在没有FGF-2的情况下支持人类干细胞，这可能提供一个标准，能够为干细胞如何发育提供关键的重要信息。只有在这之后科学家才有能力解释为什么人类胚胎干细胞系在不同的实验室产生了不同的结果。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS Published online before print August 25, 2008, doi: 10.1073/pnas.0806136105
Heparin promotes the growth of human embryonic stem cells in a defined serum-free medium
Miho K. Furue*,?,?, Jie Na?, Jamie P. Jackson?, Tetsuji Okamoto§, Mark Jones?, Duncan Baker?, Ryu-Ichiro Hata‖, Harry D. Moore?, J. Denry Sato**, and Peter W. Andrews
A major limitation in developing applications for the use of human embryonic stem cells (HESCs) is our lack of knowledge of their responses to specific cues that control self-renewal, differentiation, and lineage selection. HESCs are most commonly maintained on inactivated mouse embryonic fibroblast feeders in medium supplemented with FCS, or proprietary replacements such as knockout serum-replacement together with FGF-2. These undefined culture conditions hamper analysis of the mechanisms that control HESC behavior. We have now developed a defined serum-free medium, hESF9, for the culture of HESCs on a type I-collagen substrate without feeders. In contrast to other reported media for the culture of HESCs, this medium has a lower osmolarity (292 mosmol/liter), l-ascorbic acid-2-phosphate (0.1 μg/ml), and heparin. Insulin, transferrin, albumin conjugated with oleic acid, and FGF-2 (10 ng/ml) were the only protein components. Further, we found that HESCs would proliferate in the absence of exogenous FGF-2 if heparin was also present. However, their growth was enhanced by the addition of FGF-2 up to 10 ng/ml although higher concentrations were deleterious in the presence of heparin.
