Unmanned aerial vehicles (UAVs)—more familiarly known as drones—are quickly becoming a key piece of equipment for wildlife researchers. UAVs are safer, less costly, more efficient, and more precise than other, more traditional wildlife research methods. [Read more…]
While the moose population on Isle Royale has consistently grown in number over the past few years, the wolf population is dwindling to record low levels. Do these observations signify the end of the famous long-running Isle Royale moose-wolf population study? [Read more…]
A news program asks viewers to vote online: “Should stem cell research be banned? Yes or no?” Some people claim that stem cell therapy will revolutionize medicine. Others believe that some types of stem cell research violate ethical standards and are not justified by the potential benefits. Between these two positions exists a wide range of ideas about what is or is not acceptable. Would you know how to vote?
Using Stem Cells
Stem cells are undifferentiated cells that can regenerate themselves and develop into specialized types of cells. Stem cell research offers the hope of understanding basic cell processes and treating or even curing many diseases. However, many technical challenges must be overcome before stem cell therapy is a realistic option, and ethical issues continue to surround stem cell research.
Stem cell research offers many potential benefits.
- Studying adult stem cells may help scientists better understand how tissues develop and what goes
wrong when those tissues become diseased.
- A better understanding of the properties of stem cells may give scientists more information about
how cancer cells replace themselves and thus help scientists develop more-targeted cancer therapies.
- Stem cells could be used to grow human tissues to test the effects of drugs and chemicals.
- Stem cells may be used to replace healthy cells that are killed by radiation treatment for cancer.
- Stem cells may be used to regenerate tissues. For example, chemotherapy kills blood– producing cells in bone marrow. To replace these cells, stem cells could be used instead of the patient’s own marrow, which may contain cancer cells.
- Stem cells may be used to treat spinal cord injuries and neurodegenerative diseases, such as
Adult stem cells have been used therapeutically for years in the form of bone marrow transplants. Nevertheless, many technical challenges must still be overcome before stem cells can be used to treat a wide range of disorders. Examples are highlighted below.
Supply Stem cells can be taken from a variety of sources, including an embryo, a patient in need of treatment, a patient’ relative, or an established embryonic stem cell line. Embryonic stem cells are taken from embryos fertilized in an in vitro fertilization clinic, whereas established stem cell lines are cultures of embryonic stem cells used to grow additional stem cells that match the ones that came from the original embryo. Each source presents its own special set of ethical considerations.
Transplantation into the target area The delivery of stem cells to targeted tissues can be complex, especially if the tissues are deep inside the body. And once delivered, stem cells must “learn” to work with other cells. For instance, inserted cardiac cells must contract in unison with a patient’s heart cells.
Prevention of rejection Stem cells may be rejected if a patient’s body sees them as foreign. This problem can remain even when certain identifying proteins are removed from the cells’ membranes. The development of SCNT technology in humans could help solve this problem so that patients would not have to take drugs to suppress their immune system.
Suppression of tumor formation By their very nature, stem cells remain undifferentiated and continue to divide for long periods of time. When transplanted into an organism, many embryonic stem cells tend to form tumors. This risk must be removed before the cells can be used therapeutically.
Stem cell research and therapy do not only involve questions of what we can do. They also involve
questions about what we should do, who should benefit, and who should pay.
- Should human embryos be a source of stem cells?
- How should stem cell research be funded?
- How can the benefits of stem cell research best be shared by all people, regardless of income?
- Should insurance cover costly stem cell procedures?
UPDATES: Straight from the Headlines
- Heart Has Cellular Regeneration Ability
- Setback for New Stem Cell Treatment
- Researchers Identify Mechanisms That Allow Embryonic Stem Cells to Become Any Cell in the Human Body
Somatic Cell Nuclear Transfer
Somatic cell nuclear transfer (SCNT), also called therapeutic cloning, is a method for obtaining stem cells that has been used to clone animals. The process is still under development, however, and it has not yet been used to produce stem cells for humans. SCNT offers the hope of using a patient’s own DNA to produce stem cells that can form many types of specialized cells. Many SCNT studies have been done in mice and pigs; the diagram to the right shows how the SCNT process might be applied in human
- An unfertilized egg is taken from a female’s body, and the nucleus—containing the DNA—is removed. A cell is then taken from a patient’s body. The nucleus is removed and inserted into the egg.
- The egg is given a mild electrical stimulation, which makes it divide. The DNA comes from the patient’s nucleus, and the materials needed for division come from the egg.
- The stem cells could then be cultured and caused to differentiate into any tissue or organ needed by the patient.
Once a stem cell line is established, in theory it can continue to grow indefinitely. Researchers could use these cell lines without having to harvest more stem cells. The cell lines also could be frozen and shipped to other researchers around the world.
Cell Biologist in Action
Dr. Gail Martin
Title: Professor, Anatomy, University of California, San Francisco
Education: Ph. D., Molecular Biology, University of California, Berkeley
In 1974 Dr. Gail Martin was working at the University College in London when she made a huge advance. She developed a way to grow stem cells in a petri dish. These fragile cells were hard to work with, so Dr. Martin’s breakthrough removed a big obstacle to stem cell research. Seven years later, she made another key discovery while working in her own laboratory at the University of California, San
Francisco, in her native United States—how to harvest stem cells from mouse embryos. Her work has helped other scientists develop ways to harvest stem cells from human embryos and explore their
use in treating disorders.
Dr. Martin likes to point out that her work shows how small advances in basic biology can pay off years later in unexpected ways. She states that many people focus on cures for specific diseases, not realizing that these cures “may come from basic research in seemingly unrelated areas. What is really going to be important 20 years from now isn’t clear.”
Infections caused by drug-resistant bacteria, such as MRSA, are incredibly difficult to treat. Researchers from the Burnham Institute for Medical Research, University of Texas Southwestern Medical Center, and University of Maryland have discovered that an enzyme found in many types of bacteria can be used to kill them.
In their research, the scientists studied an enzyme in bacteria called nicotinate mononucleotide adenylytransferase (NadD). Without this enzyme, most types of bacteria are unable to survive. Using this knowledge, the scientists looked for compounds that could inhibit the activities of bacterial NadD but not affect human NadD. They discovered several compounds that inhibited NadD function in both Escherichia coli and Bacillus anthracis (anthrax). The scientists then used protein crystallography to determine the 3-D structure of NadD and its inhibiting compound. The scientists hope these studies will aid in the development of new antibacterial drugs that can over come drug-resistant bacteria.
Results of the scientists’ research was published in the August 27 edition of the journal Chemistry & Biology. Their research was funded in part by a grant provided by the National Institute of Allergy and Infectious Diseases.
Earlier last year, an interdisciplinary team of scientists met at a workshop to discuss the ethical issues related to whole-genome sequencing, particularly as it relates to human-genome research. The goal of the workshop was the develop an ethically rigorous and practical guide for scientific investigators and research ethics boards involved with human-genome research projects. At the workshop, the researchers identified four high-priority topics. These topics included:
- withdrawal from research
- return of research results
- public data release
There are many legal and ethical obligations related to human-genome research. Often, when participants agree to participate in a study involving sampling their DNA, they may not realize that their sequenced DNA may be involved in research studies beyond the one they signed up for. For example, DNA sequenced for a cancer study may later be used in a completely different study. One “problem” with current human-genome studies is that once an individual’s DNA is sequenced, it is often released into a publicly-accessible database. This information could theoretically be used by health insurance companies to determine whether or not to give you coverage. One of the major recommendations of the workshop attendees was that participants in genome-studies must be able to rescind their consent to participate at any time. At the same time, the researchers recognize that this may in some cases be impossible, given how quickly (and how far-reaching) information is disseminated. It may be necessary to regulate how the sequenced DNA of individuals is used and who exactly has access to the data.
Another ethical issue related to human-genome research is related to the findings that researchers discover from sequencing an individual’s genome. Many times, participants are told that they will not receive any information from the researcher’s about their genetic information. An ethical dilemma arises if there is information in the individual’s genetic information, such as a propensity toward the development of cancer or other disease, that if told to the participant, could have far-reaching consequences on their health and well-being (and possibly the health and well-being of their offspring as well). Researchers recommend that ethics boards develop criteria to determine when a participant should be told about certain aspects of their genetic information gleaned from sequencing their DNA.
A third ethical issue relates to the release of genetic information for use by scientists in publicly-accessible databases. One major problem with this is that once data is released into the public domain, it is basically impossible to rescind the release. Thus, even if a participant later requests to withdraw their genetic information from a study, it may be impossible to delete all their relevant data. Researchers recommend that when procuring a participant’s initial consent, they be informed that their genetic information is likely to be publicly available, and it may be impossible to remove their information from the public domain once it has been released. The workshop participants also recommended that scientists weigh the benefits and drawbacks of releasing participants’ genetic information to publicly-accessible databases with the participants’ privacy.
Given the vast number of questions scientists have about the human genome, the need for participants remains as high as ever. However, as more people become involved in these studies, there more there needs to be standards and guidelines to deal with the ethical issues that arise from genetic research. The workshop participants hope that their recommendations can serve as a starting point, though more empirical evidence and analysis is needed. As noted in an article about their recommendations, the researchers note that “the door must remain open for further reflection on these and other social concerns.”
Recommendations arising from the workshop were published online in the March 25, 2008 edition of the open-access journal PLoS Biology .
More to Explore
It is almost impossible for human hands to maneuver in a microscale environment. But now a very small robot, developed by scientists at the University of Waterloo in Ontario, Canada, may be available to accomplish these tasks. The MicroElectroMechanical Systems (MEMS) robot is less than one-fourth the size of a penny. This microrobot can place tiny objects with great precision and moves by levitation!
The MEMS robot is magnetized. Working within a magnetic field, this microrobot is made to follow a magnetic focal point. Researchers can alter the flow of current in the magnetic field, moving the focal point, and thus moving the microrobot. Grippers attached to the microrobot are remotely controlled by a laser beam. When the laser is turned on and aimed at the grippers, the laser heats the grippers, making them open. When the laser is turned off, the grippers cool and close.
Because this microrobot moves within a magnetic field, it can float in the air, or levitate. This technology allows the microrobot to be positioned near hazardous or toxic surfaces without making contact. It can also avoid contamination in especially sensitive environments such as sterilized rooms, making it suitable for use in medical applications such as micro-surgery.
More to Explore
A team of scientists at Penn State University is using a new approach to understand cells. They are starting from scratch. Many scientists start with something complex, such as an entire cell, and then delete genes one at a time to find what those genes do in the cell. Dr. Christine Keating, who led the research team, points out that her group is doing just the opposite. According to Keating, they are starting with a simple model cell to find out what is needed to simulate the most basic cell functions. Keating emphasizes that their goal is not to make a real cell. Rather, they want to understand the physical principles that govern biological systems.
The teams model cell is made up of cytoplasm surrounded by a cell membrane. The cytoplasm is a mixture of two somewhat gelatinous fluids. The two fluids do not mix, so one surrounds the other much as egg white surrounds an egg yolk. The cell membrane is made up of several types of lipids.
Researchers exposed the model cell to a concentrated sugar solution. Water diffused out of the cell and into the surrounding sugar solution. As a result, the volume of the cell decreased, leaving a membrane that was now too large for its contents. The cell changed to a budded form that looks like the two overlapping circles of a Venn diagram. The two fluids separated from each other based on their different interactions with the cell membrane. The cell exhibited a distinct polarity: one substance filled the main cell body, and the other substance filled the cell bud. “Polarity is critical to development,” stated Keating. “It is an important first step . . . in which different cells perform different functions.”
The next step for the research team involves making a cascade in polarity. “Now,” says Keating, “we want to find out what will happen if, for example, we add an enzyme whose activity depends on the compositions of the cytoplasm and cell membrane.”