魔兽世界7.0休闲职业:精子有望治愈糖尿病

作者：卡丽·阿诺德 本文发表于2010年12月13日

PHILADELPHIA, PENNSYLVANIA—Men with type 1 diabetes may one day be able to use the stem cells that become sperm to replace their insulin-producing pancreatic cells. Such transplants would eliminate the need for frequent daily insulin injections to control blood sugar.

来自宾西法尼亚，费城的报道：患有一型糖尿病的男性患者未来将有可能利用形成精子的人体干细胞对其胰岛细胞进行置换，这将减少病患为控制血糖而对日常胰岛素注射的需要。

Type 1 diabetes occurs when the immune system attacks and destroys insulin-producing islet cells in the pancreas. Without insulin to help cells absorb blood glucose, a person can't use energy from food. Untreated type 1 diabetes is always fatal, but regular insulin injections and blood-sugar monitoring can allow patients to have fairly normal lives.

一型糖尿病的发病机理大致为：人体免疫系统攻击并破坏了胰腺中制造胰岛素的胰岛细胞。胰岛素帮助人体细胞吸收血糖，如果胰岛素缺乏，人体将无法利用食物产生的能量。因此，若不进行治疗，一型糖尿病通常来说是致命的。不过规律注射胰岛素并进行血糖监测可以使病人维持正常生活。

Occasionally, insulin injections aren't enough to keep type 1 diabetes in check, however. So in the late 1990s, researchers at the University of Alberta in Canada began transplanting islet cells from cadavers into diabetics. This isn't an ideal solution, though, as recipients have to remain on immune-suppressing medication for the rest of their lives to prevent transplant rejection and usually still require some insulin injections.

然而，偶尔也会出现的情况是，注射胰岛素并不足以令一型糖尿病患者的血糖水平处于良好受控状态。因此，在上世纪90年代末期，加拿大阿尔伯塔大学的研究人员首次尝试将尸体中的胰岛细胞移植给糖尿病患者。但这并不是一个理想的解决办法，因为受体将不得不在余生内一直服用免疫抑制剂来对抗排斥反应，并且通常仍会进行一些胰岛素注射。

Stem cell biologist G. Ian Gallicano of Georgetown University in Washington, D.C., and colleagues believe they have found a method that would give diabetics the advantages of islet cell transplantation without the need for immunosuppressant drugs. Millions of sperm cells are created each day from stem cells in the testes known as spermatogonial stem cells (SSCs). The researchers harvested SSCs from human testicular tissue and engineered them to become pluripotent stem cells, which have the capability to specialize into any type of cell, a process that took 2 weeks. Then, the researchers prodded these stem cells to develop into islet cells.

位于美国华盛顿的乔治城大学干细胞生物学家G·伊恩·加利卡诺和他的同事们相信，他们已经找到了一种让糖尿病患者享受到胰岛细胞移植的效果但无需服用免疫抑制剂的方法。每天有数以百万计的精子细胞经由被称为SSCs（精原干细胞）的人体干细胞生成。研究人员从人体睾丸组织中采集出精原干细胞并将其改造成多能干细胞，这个过程需要两周时间，这种多能干细胞具备形成任何类型人体细胞的能力。然后，研究人员将这些多能干细胞制成胰岛细胞。

As they reported here yesterday at the annual meeting of the American Society for Cell Biology, Gallicano and colleagues transplanted the engineered human islet cells into diabetic mice that don't have an immune system and so can't attack the inserted cells. The transplants lowered the mice's high blood glucose levels, a good sign that the cells would do the same thing in humans. 

昨日加利卡诺及其同事在美国细胞生物协会年度会议上做报告称，他们将由生物工程改造成的人体胰岛细胞移植给糖尿病实验鼠，老鼠没有免疫系统因此也无法攻击植入细胞。移植降低了老鼠的高血糖水平，这是个非常好的迹象，它表明可以在人类身上做同样的事情。

Gallicano cautions, however, that the technique isn't ready for people just yet. "We don't get enough insulin from each cell to cure diabetes in humans." 

不过加利卡诺也警告说，有关人体实验技术还不成熟：“我们无法从细胞中获取足够多的胰岛素来治疗人的糖尿病。”

That's a concern echoed by Sheng Ding, a biochemist at The Scripps Research Institute in San Diego, California, who wasn't involved in the research. Before the technique is ready for the clinic, he says, researchers will need to increase insulin production in the transplanted cells. Still, Ding says, "This represents one direction to pursue for ultimately curing type 1 diabetes."

斯克利普斯研究所（位于加州圣地亚哥）的生物化学家盛丁回应了这个问题，他本人并未参与此项研究。他说：“在用于临床研究的技术成熟之前，研究人员需要增加移植细胞的胰岛素产出量。不过，此项研究为最终治愈一型糖尿病提供了一个方向。”

This isn't the first attempt to treat or cure diabetes with stem cells. Researchers had previously used cells from skin or other tissues to create a slightly different type of stem cell, known as an induced pluripotent stem (iPS) cell, which could then go on to replace the damaged islet cells. Using iPS cells does have some advantages, Gallicano says. They don't require an invasive procedure to obtain, and they work for both sexes. However, researchers need to add four genes to morph cells into iPS cells. The genes don't always insert in the right place, which could cause cancer or cell death, he says.

这并非利用干细胞治疗糖尿病的首次尝试。科研人员曾用皮肤和其它组织细胞制造出略有不同的干细胞类型，这种干细胞被称为IPS（诱导多能性干细胞），它可替代受损的胰岛细胞。加利卡诺说，利用IPS确实有些优点，首先获取它无需进行侵入性程序，其次它可同时作用于两性病患。可是，令细胞变形为IPS，研究人员需要给细胞增加4组基因片段，而这些基因常常不能被准确注入正确位置，如是可致癌或引起细胞死亡。

The human SSCs, though, found in men only, are already stem cells and don't need those four genes turned on. "We don't have to do anything to make them pluripotent except take them out of their niche" in the testes, Gallicano says. 

而发现于男性体内的人体精原干细胞，本身就是干细胞了，不需要额外增加那4个基因组将其改造形成。在实验过程中加利卡诺说：“除了将其移出其生态位，我们不必做其它任何事情。”

The researchers hope that they can find a method that would benefit female diabetics as well. Gallicano says he sees no reason why egg precursor stem cells can't also be used. One major difference is that the egg stem cells have only one copy of every gene, whereas the SSCs have two copies, like other cells in the body, which makes it easier to apply the technique to SSCs. 

科研人员希望他们也能发现一种造福于女性糖尿病患者的方法。加利卡诺说，他看不出有什么理由令卵原干细胞无法利用。卵原干细胞不同于精原干细胞的最大区别是，前者的每个基因只有一组拷贝，而后者SSC有两组。像体内别的细胞一样，两组基因拷贝将令科研技术在精原干细胞身上更容易运用。

There's one more hurdle, says Gallicano, which is finding out whether the immune system, which has already created antibodies against the body's islet cells, will attack the transplanted cells as well.

还有一项障碍，加利卡诺说，他们发现无论免疫系统是否已经产生了对抗体内胰岛细胞的抗体，它都会攻击移植细胞。