問題詳情
請依下文回答第 46 題至第 50 題Umbilical cord blood was once discarded as waste material but is now known to be a useful source of blood stemcells. After a baby is born, cord blood is left in the umbilical cord and placenta. It is easy to collect, with no risk to themother or baby. It contains haematopoietic (blood) stem cells: rare cells normally found in the bone marrow.Haematopoietic stem cells (HSCs) can make every type of cell in the blood – red cells, white cells and platelets. Theyhave been used for many years in bone marrow transplants to treat blood diseases.Cord blood is used to treat children with cancerous blood disorders such as leukemia, or genetic blood diseaseslike Fanconi anemia. The cord blood is transplanted into the patient, where the HSCs can make new, healthy bloodcells to replace those damaged by the patient’s disease or by a medical treatment such as chemotherapy for cancer. Inthis way, cord blood offers a useful alternative to bone marrow transplants for some patients. It also seems to be lesslikely than bone marrow to cause immune rejection or complications such as Graft versus Host Disease.However, cord blood transplants also have limitations. Treatment of adults with cord blood has so far proved tobe very challenging, despite some successes. Cord blood can also only be used to treat blood diseases. No therapies fornon-blood-related diseases have yet been developed using HSCs from either cord blood or adult bone marrow. A majorlimitation of cord blood transplantation is that the blood obtained from a single umbilical cord does not contain asmany haematopoeitic stem cells as a bone marrow donation. A transplant containing too few HSCs may fail or couldlead to slow formation of new blood in the body in the early days after transplantation. This has been partiallyovercome by transplanting blood from two umbilical cords into larger children and adults. Some researchers have alsotried to increase the total number of HSCs obtained from each umbilical cord by collecting additional blood from theplacenta. Much research is focused on trying to increase the number of HSCs that can be obtained from one cord bloodsample by growing and multiplying the cells in the laboratory. This is known as “ex vivo expansion”. Severalpreliminary clinical trials using this technique are underway. The results so far are mixed: some results suggest that exvivo expansion reduces the time taken for new blood cells to appear in the body after transplantation; however, adultpatients still appear to need blood from two umbilical cords. Neither solution is entirely satisfactory.
【題組】46 What is the main idea of this passage?
(A)Cord blood is a panacea that can cure all diseases.
(B)Cord blood has a good application but it also has limitations.
(C)Cord blood treatment is only applicable to children.
(D)Cord blood is much easier and safer to collect than bone marrow.
參考答案
答案：B
難度：適中0.6
統計：A(3),B(12),C(3),D(2),E(0)
用户評論
【Dorothy】評論
臍帶血曾作為廢物被丟棄，但現在已知是血液幹細胞的有用來源。嬰兒出生後，臍帶血和胎盤留在臍帶和胎盤中。它很容易收集，對母親或嬰兒沒有任何風險。它含有造血（血液）幹細胞：通常在骨髓中發現的稀有細胞。造血幹細胞（HSCs）可以製造血液中的各種細胞 - 紅細胞，白細胞和血小板。它們已經在骨髓移植中使用多年來治療血液疾病。臍帶血用於治療患有癌症血液疾病的兒童，例如白血病，或範可尼貧血等遺傳性血液疾病。將臍帶血移植到患者體內，其中HSC可以製造新的，健康的血細胞以替代由患者疾病損害的那些或通過諸如癌症化學療法的醫學治療。通過這種方式，臍帶血為某些患者的骨髓移植提供了有用的替代方案。它似乎也不如骨髓引起免疫排斥或併發...