透過把未成熟的人類肝臟細胞「播種」到動物肝臟的支架上進行培育，研究人員成功在實驗室中創造出核桃大小的迷你人造肝臟。該研究計畫主任、美國北卡羅來納州維克森林再生醫學研究所副教授索克說，他們對該研究呈現的可能性深感興奮，但也強調目前仍處於研究初步階段；在人造肝真正能造福病患之前，勢必還得克服許多技術障礙，包括得同時製造大量人造肝臟，以及確定這些人造肝臟安全無虞。
索克的同僚貝皮斯塔則表示，他們希望這些人造肝臟一旦移植到人體後，仍能持續發展以及維持正常功能。
研究人員解釋，他們利用一種溫和洗滌劑，去除掉雪貂肝臟上的細胞，使之只剩下膠原蛋白支架與血管；接著將未成熟的人類肝臟細胞「播種」到支架上。雪貂肝臟支架隨著這些細胞成長提供塑形與結構，至於血管則連接到生物反應器，以便提供氧氣、養分與帶走廢物。研究人員表示，人造肝臟在被放到生物反應器內培育一週後開始生長，而且功能與正常的人類肝臟無異。
此一技術若要能真正造福病患，至少還要5年，甚至更久。研究人員表示，接下來的步驟是觀察這些人造肝臟被移植回雪貂體內後，能否持續維持其功能，屆時才能考慮這種人造肝臟能否用於人類。美國波士頓的麻薩諸塞州綜合醫院的科學家，今年稍早也曾利用類似的動物支架技術，成功培育出迷你老鼠肝臟，並將之移植到活鼠內。接受移植的老鼠存活了數小時。
圖為科學家將動物肝臟去除細胞(左圖)，剩下膠原蛋白的骨架(中間)，再經由血管植入人類未成熟的肝臟細胞(右圖)
ScienceDaily (Oct. 9, 2010) — Researchers at Karolinska Institutet have shown how stem cells, together with other cells, repair damaged tissue in the mouse spinal cord. The results are of potential significance to the development of therapies for spinal cord injury.
There is hope that damage to the spinal cord and brain will one day be treatable using stem cells (i.e. immature cells that can develop into different cell types). Stem cell-like cells have been found in most parts of the adult human nervous system, although it is still unclear how much they contribute to the formation of new, functioning cells in adult individuals.
A joint study by Professor Jonas Frisén's research group at Karolinska Institutet and their colleagues from France and Japan, and published in Cell Stem Cell, shows how stem cells and several other cell types contribute to the formation of new spinal cord cells in mice and how this changes dramatically after trauma.
The research group has identified a type of stem cell, called an ependymal cell, in the spinal cord. They show that these cells are inactive in the healthy spinal cord, and that the cell formation that takes place does so mainly through the division of more mature cells. When the spinal cord is injured, however, these stem cells are activated to become the dominant source of new cells.
The stem cells then give rise to cells that form scar tissue and to a type of support cell that is an important component of spinal cord functionality. The scientists also show that a certain family of mature cells known as astrocytes produce large numbers of scar-forming cells after injury.
"The stem cells have a certain positive effect following injury, but not enough for spinal cord functionality to be restored," says Jonas Frisén. "One interesting question now is whether pharmaceutical compounds can be identified to stimulate the cells to form more support cells in order to improve functional recovery after a spinal trauma."
