Human Embryonic Stem Cells
Despite the ethical and political controversies surrounding human embryonic stem cells, researchers are moving forward to develop these cells to alleviate diseases and repair the body. Advanced Cell Technology (www.advancedcell.com) has several projects using hESCs they would like to move into the clinic. “We have published a paper showing, for the first time, that we can create RPE (retinal pigment epithelium) from human embryonic stem cells,” says Robert Lanza, M.D., vp, research and scientific development.
RPE is the layer of cells that maintains the photoreceptors, cones, and rods and enables vision. “We’re hoping to transplant these cells to attenuate vision loss or prevent further progress of macular degeneration,” he adds. In addition, a recent paper by Dr. Lanza’s group shows the same RPE can significantly attenuate visual loss in animal models due to RPE loss.
“We were able to significantly rescue the photo receptors and saw about 100% improvement in visual acuity in the animals transplanted with these cells,” says Dr. Lanza. Furthermore, he reports that histopathology shows cones and rods in the petri dish. “In fact, we actually see little eyeballs. We’ve now been able to create precursors that create photo receptors, and the hope is to reverse blindness.”
Another project under development involves creating certain hematopoetic precursors from hECs. “We have created a hemangioblast, which has been theorized to form our entire immune, vascular, and hematopoetic system.” These cells are being studied in various animal models. “We found that we can cut the death rate after a heart attack in half and restore blood flow to limbs that would otherwise require amputation, within a month after injection,” states Dr. Lanza. In addition, the cells have accelerated the parameters of wound healing threefold.
The company also developed a technology using a single blastomere from human embryos to create cell lines without damaging or destroying the embryo. Dr. Lanza says this is important because it alleviates some of the ethical concerns. Also, there remains hope that the government will allow these cells to be added and used by researchers. “It has only been recently that some of the controversy has subsided. Many think this research is not going to materialize for years to come, but we are filing an IND at the end of this year.”
Bioengineering future therapies will potentially include human cells. However, there are many difficulties involved in finding appropriate cells in the right amounts and quality to study and make scientific decisions on whether the cells mimic the system in the body. Also, “you want to acquire human cells and tissues in an ethical manner, so you have to have consent,” states Nancy Dock, Ph.D., director of tissue acquisition at Lonza Walkersville (www.lonza.com), which offers two cell model lines, Clonetics® and Poietics™, for research.
“You want to make sure the person the cells derived from has consented, as well as next of kin, and that the cells don’t come from someone with a disease that could interfere with the cell’s functioning and scientific findings. Companies like ours deal with the issues of how tissues and organs are accessed all the time,” states Dr. Dock. “Part of our approach is to make sure researchers are aware that they need to go through this process upfront and get consent. We’re encouraging people to think about that at the beginning of a project, not the end.”
Dr. Dock notes that current screening tools are good and help ensure organs and tissues are used safely. She adds that part of the focus of the meeting will be to look at novel ways of appropriately obtaining human cells and expanding them, as well as other issues, like cell preservation. “You may be able to get a lot of cells, but they may not replicate or grow well,” states Dr. Dock. Cell sampling and tissue biopsy are also big issues.
“If you are looking to make a cure for a particular disease and it has to do with how well a cell functions, then you want to make sure you have representative examples of those cells that reflect the whole population. That’s not so easy. People have been exposed to many different factors throughout their lives. You have to make sure what you’ve isolated is the correct cell, and it does what it’s supposed to do in the lab. Then you must infer from that what the cell is going to do in the body.”