Just because I am an embryonic stem cell researcher, don't think I am neglecting adult stem cells. Here's a good paper that combines the methods of gene therapy with the strengths of stem cell biology:
Hematopoietic stem cells are responsible for replenishing the entire hematopoietic system, which consists of multiple cell types including oxygen carrying erythrocytes (red blood cells) and of course disease fighting lymphocytes (white blood cells). What is amazing about hematopoietic stem cells is that a single one of them can recreate the entire system. This is mostly theoretical, but in practice a few cells are enough to accomplish the job.
This feature of the hematopoietic stem cells is already used in cancer treatment. In some cases, some stem cells are removed, all the other cells killed with extreme treatment and then the patient's blood is replenished from the saved cells.
Next logical step is to use this to fix other blood diseases, like hemophilia. One could take some stem cells out, fix a few, inject them back to the patient after killing all the defective cells and the newly produced cells won't have the disease. This is exactly what the researchers did in this study. Only, instead of fixing broken cells they broke normal cells. Let me explain.
Remember AIDS (Acquired ImmunoDeficiency Syndrome)? AIDS is caused by this virus called HIV. HIV infects immune system, lymphocytes die, immune system falters, patients can't fight simplest diseases and eventually succumb to one of these. However, HIV can't just go through the cell membrane, it needs a gateway of some sort to accomplish its evil goal. If one could find this gateway and break it, one could stop the infection process.
A natural experiment (a.k.a. a human being) provided the clue. Scientists realized that people, who had a broken CCR5 gene were refractory to HIV infections and they figured HIV needed CCR5 to enter the cell. Following this clue, Schleifman and colleagues broke the CCR5 gene in some human hematopoietic stem cells (we won't go into the details, but that is equally impressive) and showed that these cells and the lymphocytes they made were now resistant to infection. In their study they injected the cells into rats, but in a clinical setting this can be used to increase the numbers of virus-resistant lymphocytes and thus shore up the immune system.
I don't see any obvious safety concerns with moving this study to the clinics. No viruses were used and hematopoietic stem cell transplantation is routinely done. The major hurdle here will be the efficiency and the cost. Let's see how long it will take to figure that one out.
A natural experiment (a.k.a. a human being) provided the clue. Scientists realized that people, who had a broken CCR5 gene were refractory to HIV infections and they figured HIV needed CCR5 to enter the cell. Following this clue, Schleifman and colleagues broke the CCR5 gene in some human hematopoietic stem cells (we won't go into the details, but that is equally impressive) and showed that these cells and the lymphocytes they made were now resistant to infection. In their study they injected the cells into rats, but in a clinical setting this can be used to increase the numbers of virus-resistant lymphocytes and thus shore up the immune system.
I don't see any obvious safety concerns with moving this study to the clinics. No viruses were used and hematopoietic stem cell transplantation is routinely done. The major hurdle here will be the efficiency and the cost. Let's see how long it will take to figure that one out.
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