several of which have specialized roles in the blood.

其中幾種在血液中有特定的作用

In the early 1960s it was shown that if bone marrow was taken from one mouse and transplanted into another,

1960年代前期就被發現當把一隻老鼠身上的骨髓取出並移植到另一隻老鼠體內

rare and unspecialized cells could travel to the spleen where they would divide and form small colonies

罕見且非特異的細胞就會到達脾臟, 分裂並且形成小的細胞集落

These colonies contained a mixture of different blood cell types.

這些細胞群落含有不同類型的血液細胞

Incredibly when these colonies were removed and retransplanted,

神奇的是當這些細胞集落被取出並且再進行一次移植

these rare cells formed new colonies in the spleen of a second mouse.

這些罕見的細胞會在第二隻老鼠的脾臟內形成新的細胞集落

These reveal two defining properties of a stem cell.

以上顯示了兩種幹細胞的特質

First a stem cell must be able to self renew. That is, it must be able to divide and give rise to more cells like itself.

第一, 幹細胞必須能夠自我更新, 也就是說, 他必須能夠自我分裂後產生更多跟自己一樣的細胞

Second, it must be able to differentiate. In other words it must be able to divide and give rise to specialized cells.

第二. 他必須能夠行細胞分化, 換句話說他必須能夠分裂出其他特定的細胞

Since these early experiments, many different types of stem cells have been discovered

由於這些早期的實驗, 我們已經發現了許多不同類型的幹細胞

And this general definition applies to all of them.

而這個廣義的定義適用於所有的幹細胞

Following fertilization, the developing embryo contains a group of cells

受精之後, 發育中的胚胎含有一組細胞

known as the "inner cell mass" that will eventually go on to form all tissues in the body.

被稱作''內細胞團'', 他們最後將會形成身體所有的組織

However at the early stage of development these cells have not yet committed to become a specific type of cell

然而, 在早期的發育階段, 這些細胞還尚未形成特定種類的細胞

and are said to be in an undifferentiated state.

而被認為是屬於未分化狀態

If the cells of the "inner cell mass" are isolated

如果內細胞團內的細胞被分離出來

they can grow indefinitely in a plastic dish and maintain this undifferentiated state.

他們可以無止盡的在細胞培養皿內生長, 並且維持這種未分化的狀態

These cells are known as "embryonic stem cells" or ES cells

這些細胞被稱作''胚胎幹細胞'' 或者ES細胞

Like cells in the developing embryo

就像發育中胚胎內的細胞

ES cells retain the ability to form any type of cell in the adult body

胚胎幹細胞保留著能夠在成體內形成任何種類細胞的能力

Thus ES cells are said to be "pluripotent"

也因為如此胚胎幹細胞被認為是''多功能的''

By studying the signals required to control how ES cells develop into specific cell types

藉由研究控制ES細胞如何發展成特定細胞所需要的訊號

scientists may be able to develop therapies capable of restoring damaged tissues

科學家們可能發展出可以使受損組織恢復的療法

Most of the cells in our bodies are not stem cells.

我們體內大多數的細胞都不是幹細胞

For example blood and skin cells have become specialized to perform a specific function in the body.

例如血液與皮膚細胞已經被分化成在體內執行特定功能

By a process known as differentiation, that is normally not reversible.

這一個分化的過程, 通常都是不可逆的

However, if some adults cells are taken grown in plastic dishes and given specific genetic instructions over time,

然而, 如果將依些將成熟的細胞培養在培養皿中並且在其生長過程中給予特定的遺傳指令

a small number of these cells will reverse from their differentiated state and develop the ability to redifferentiate into any cell type in the body.

少數的細胞會從他原本的狀態逆轉成具有能夠分化成身體內任何細胞的能力

This newfound ability is known as "pluripotentcy", and therefore these cells are known as "induced pluripotent stem cells" or IPS cells.

這種新發現的能力稱作''多能性'', 因此這些細胞又被稱作''誘導多能型幹細胞''或是''IPS細胞''

The creation of IPS cells from individual patients may one day allows us to develop replacement tissues that are a perfect genetic match to the patient.

來自患者的IPS細胞在未來可能讓我們開發出和患者遺傳匹配的替代的組織

In addition, the creation of IPS cells from patients with specific diseases will allow scientists to develop new drugs to treat a wide variety of disorders.

此外從特定疾病患者身上取得的IPS細胞能夠讓科學家開發新的藥物來治療各種疾病