Stem cell laws and policy in the United States have had a complicated legal and political history.

Stem cells are cells found in all multi-cellular organisms. They were isolated in mice in 1981, and in humans in 1998.[1] In humans there are many types of stem cells, each with varying levels of potency. Potency is a measure of a cell's differentiation potential, or the number of other cell types that can be made from that stem cell. Embryonic stem cells are pluripotent stem cells derived from the inner cell mass of the blastocyst. These stem cells can differentiate into all other cells in the human body and are the subject of much scientific research. However, since they must be derived from early human embryos their production and use in research has been a hotly debated topic.

Stem cell treatments are a type of cell therapy that introduce new cells into adult bodies for possible treatment of cancer, diabetes, neurological disorders and other medical conditions. Stem cells have been used to repair tissue damaged by disease or age.[2] Cloning also might be done with stem cells. Pluripotent stem cells can also be derived from Somatic cell nuclear transfer which is a laboratory technique where a clone embryo is created from a donor nucleus. Somatic cell nuclear transfer is also tightly regulated amongst various countries.

Until recently, the principal source of human embryonic stem cells has been donated embryos from fertility clinics. In January 2007, researchers at Wake Forest University reported that "stem cells drawn from amniotic fluid donated by pregnant women hold much of the same promise as embryonic stem cells."[1]

In 2000, the NIH, under the administration of President Bill Clinton, issued "guidelines that allow federal funding of embryonic stem-cell research."[1]

In 1973, Roe v. Wade legalized abortion in the United States. Five years later, the first successful human in vitro fertilization resulted in the birth of Louise Brown in England. These developments prompted the federal government to create regulations barring the use of federal funds for research that experimented on human embryos.[3] In 1995, the NIH Human Embryo Research Panel advised the administration of President Bill Clinton to permit federal funding for research on embryos left over from in vitro fertility treatments and also recommended federal funding of research on embryos specifically created for experimentation. In response to the panel's recommendations, the Clinton administration, citing moral and ethical concerns, declined to fund research on embryos created solely for research purposes,[4] but did agree to fund research on left-over embryos created by in vitro fertility treatments. At this point, the Congress intervened and passed the DickeyWicker Amendment in 1995 (the final bill, which included the Dickey Amendment, was signed into law by Bill Clinton) which prohibited any federal funding for the Department of Health and Human Services be used for research that resulted in the destruction of an embryo regardless of the source of that embryo. In 1998, privately funded research led to the breakthrough discovery of human Embryonic stem cells (hESC).

No federal law ever did ban stem cell research in the United States, but only placed restrictions on funding and use, under Congress's power to spend.[5]

In February 2001, George W. Bush requested a review of the NIH's guidelines, and after a policy discussion within his circle of supporters, implemented a policy in August of that year to limit the number of embryonic stem cell lines that could be used for research.[1] (While he claimed that 78 lines would qualify for federal funding, only 19 lines were actually available.[1])

In April 2004, 206 members of Congress, including many moderate Republicans, signed a letter urging President Bush to expand federal funding of embryonic stem cell research beyond what Bush had already supported.

In May 2005, the House of Representatives voted 238-194 to loosen the limitations on federally funded embryonic stem-cell research by allowing government-funded research on surplus frozen embryos from in vitro fertilization clinics to be used for stem cell research with the permission of donors despite Bush's promise to veto if passed. [2] On July 29, 2005, Senate Majority Leader William H. Frist (R-TN), announced that he too favored loosening restrictions on federal funding of embryonic stem cell research.[6] On July 18, 2006, the Senate passed three different bills concerning stem cell research. The Senate passed the first bill, 63-37, which would have made it legal for the Federal government to spend Federal money on embryonic stem cell research that uses embryos left over from in vitro fertilization procedures. On July 19, 2006 President Bush vetoed this bill. The second bill makes it illegal to create, grow, and abort fetuses for research purposes. The third bill would encourage research that would isolate pluripotent, i.e., embryonic-like, stem cells without the destruction of human embryos.

The National Institutes of Health has hundreds of funding opportunities for researchers interested in hESC.[7] In 2005 the NIH funded $607 million worth of stem cell research, of which $39 million was specifically used for hESC.[8]

During Bush's second term, in July 2006, he used his first Presidential veto on the Stem Cell Research Enhancement Act. The Stem Cell Research Enhancement Act was the name of two similar bills, and both were vetoed by President George W. Bush and were not enacted into law. New Jersey congressman Chris Smith wrote a Stem Cell Therapeutic and Research Act of 2005, which was signed into law by President Bush. It provided $265 million for adult stem cell therapy, umbilical cord blood and bone marrow treatment, and authorized $79 million for the collection of cord blood stem cells.

By executive order on March 9, 2009, President Barack Obama removed certain restrictions on federal funding for research involving new lines of human embryonic stem cells.[9] Prior to President Obama's executive order, federal funding was limited to non-embryonic stem cell research and embryonic stem cell research based upon embryonic stem cell lines in existence prior to August 9, 2001. Federal funding originating from current appropriations to the Department of Health and Human Services (including the National Institutes of Health) under the Omnibus Appropriations Act of 2009, remains prohibited under the DickeyWicker Amendment for (1) the creation of a human embryo for research purposes; or (2) research in which a human embryo or embryos are destroyed, discarded, or knowingly subjected to risk of injury or death greater than that allowed for research on fetuses in utero.

In a speech before signing the executive order, President Obama noted the following:

Today, with the Executive Order I am about to sign, we will bring the change that so many scientists and researchers; doctors and innovators; patients and loved ones have hoped for, and fought for, these past eight years: we will lift the ban on federal funding for promising embryonic stem cell research. We will vigorously support scientists who pursue this research. And we will aim for America to lead the world in the discoveries it one day may yield.[10]

In 2011, a United States District Court "threw out a lawsuit that challenged the use of federal funds for embryonic stem cell research."[11] The decision was a case on remand from the United States Court of Appeals for the District of Columbia Circuit.[11][12]

S1909/A2840 is a bill that was passed by the New Jersey legislature in December 2003, and signed into law by Governor James McGreevey on January 4, 2004, that permits human cloning for the purpose of developing and harvesting human stem cells. Specifically, it legalizes the process of cloning a human embryo, and implanting the clone into a womb, provided that the clone is then aborted and used for medical research. Missouri Constitutional Amendment 2 (2006) (Missouri Amendment Two) was a 2006 law that legalized certain forms of embryonic stem cell research in the state.

California voters in November 2004 approved Proposition 71, creating a US$3 billion state taxpayer-funded institute for stem cell research, the California Institute for Regenerative Medicine. It hopes to provide $300 million a year. However, as of June 6, 2006, there were delays in the implementation of the California program and it is believed that the delays will continue for the significant future. [3] On July 21, 2006, Governor Arnold Schwarzenegger (R-Calif.) authorized $150 million in loans to the Institute in an attempt to jump start the process of funding research.[13]

Several states, in what was initially believed to be a national migration of biotech researchers to California,[14] have shown interest in providing their own funding support of embryonic and adult stem cell research. These states include Connecticut [4], Florida, Illinois, Massachusetts [5], Missouri, New Hampshire, New York, Pennsylvania, Texas [6] [7], Washington, and Wisconsin.

Other states have (or have shown interest in) additional restrictions or even complete bans on embryonic stem cell research. These states include Arkansas, Iowa, Kansas, Louisiana, Nebraska, North Dakota, South Dakota, and Virginia. (States play catch-up on stem cells, USA Today, December 2004) Arkansas, Indiana, Louisiana, Michigan, North Dakota and South Dakota have passed laws to "prohibit the creation or destruction of human embryos for medical research."[5]

Policy stances on stem cell research of various political leaders in the United States have not always been predictable.

As a rule, most Democratic Party leaders and high-profile supporters and even rank and file members have pushed for laws and policies almost exclusively favoring embryonic stem cell research.[16] President Bill Clinton supported the NIH's guidelines in 2000.[1] Both the major candidates in 2008 had supported the 2005 and 2007 bills, in particular Hillary Rodham Clinton, Bill Clinton's First Lady, then U. S. Senator for New York,[17] and Barack Obama, then U.S. Senator for Illinois, who promised to sign the EFCA into law, and was a cosponsor of such bills.[18] Massachusetts governor Deval Patrick is also a proponent of embryonic stem cell research. There have been some Democrats who have asked for boundaries be placed on human embryo use. For example, Carolyn McCarthy has publicly stated she only supports using human embryos "that would be discarded".[19][20]

The Republicans largely oppose embryonic stem cell research in favor of adult stem cell research which has already produced cures and treatments for cancer and paralysis for example, but there are some high-profile exceptions who offer qualified support for some embryonic stem cell research.[5] Prominent Republican leaders against embryonic stem cell research include Sarah Palin, Jim Talent, Rick Santorum, and Sam Brownback.[5] In July 2001:

Sen. Bill Frist (R-TN) and Sen. Orrin Hatch (R-UT), a vocal abortion opponent, call[ed] for limited federal funding for embryonic stem-cell research.... House Speaker Dennis Hastert (R-IL) and other Republican House leaders [came] out in opposition to federal funding for embryonic stem cell research.

2008 GOP Presidential Candidate John McCain was a member of The Republican Main Street Partnership, and supported embryonic stem cell research,[5] despite his earlier opposition.[21] In July 2008 he said, "At the moment I support stem cell research [because of] the potential it has for curing some of the most terrible diseases that afflict mankind."[22] In 2007, in what he described as "a very agonizing and tough decision," he voted to allow research using human embryos left over from fertility treatments.[23] Former First Lady Nancy Reagan and Senator Orrin Hatch also support stem cell research, after first opposing the issue.[5] Former Senator Frist also supports stem cell research, despite having initially supported past restrictions on embryonic stem cell research. 2008 V.P. candidate Palin opposed embryonic stem cell research, which she said causes the destruction of life, thus this research is inconsistent with her pro-life position and she does not support it.[24]

A few moderates or Libertarians support such research with limits. Lincoln Chafee supported federal funding for embryonic stem cell research. Ron Paul, a Republican congressman, physician, and Libertarian and Independent candidate for President, has sponsored much legislation, and has had quite complex positions.

Several studies have examined the impact of changing funding policies on scientific research in the US and the development of new cell therapies by industry. For example, studies have highlighted an immediate and sizable drop in research productivity of US-based researchers as compared to researchers based elsewhere during the years after the enactment in August 2001 of federal funding restrictions on research involving new embryonic stem cell lines.[25][26][27][28] US knowledge production in the human embryonic stem cell field fell 35 to 40 per cent below anticipated levels, and measured in terms of forward citations to core research publications in the field, US-based follow-on work in the human embryonic stem cell research field declined by nearly 59 per cent relative to non-US-based research over the period 2001-2003.[25] During this period US based firms were also less likely to launch new therapeutic product development projects in the cell therapy field than firms outside the US, and were more likely to discontinue clinical trials for new cell therapies that were already under way.[29] All these effects were reversed as the funding environment for stem cell research in the US became more favourable during the second half of the 2000s.

In 2005, the United States National Academies released its Guidelines for Human Embryonic Stem Cell Research. These Guidelines were prepared to enhance the integrity of human embryonic stem cell research in the public's perception and in actuality by encouraging responsible practices in the conduct of that research. The National Academies has subsequently named the Human Embryonic Stem Cell Research Advisory Committee to keep the Guidelines up-to-date.[30]

The guidelines preserve two primary principles. First, that hESC research has the potential to improve our understanding of human health and discover new ways to treat illness. Second, that individuals donating embryos should do so freely, with voluntary and informed consent. The guidelines implement executive order 13505, and apply to hESC research receiving funds from the NIH. The guidelines detail safeguards to protect donating individuals by acquiring informed consent and protecting their identity. In addition, the guidelines contain multiple sections applying to embryos donated in the US and abroad, both before and after the effective date of the guidelines.[31]

The NIH guidelines define which hESC research is eligible to receive NIH funding through a series of regulations which applicants for funding must adhere to. Applicants proposing research, may use stem cell lines that are posted on the NIH registry, or may submit an assurance of compliance with section II of the guidelines. Section II is applicable to stem cells derived from human embryos.[31]

For the purposes of section II of the NIH guidelines, the following requirements must be met. First, the hESCs should have been derived from embryos created using an in vitro fertilization procedure for reproductive purposes, and no longer needed for this purpose. Second, the donors who sought reproductive treatment have given written consent for the embryos to be used for research purposes. Third, all written consent forms and other documentation must be provided.[31]

Documentation must be provided regarding the following: All options available to the healthcare facility regarding the embryos in question were explained to the individual who sought reproductive treatment. No payments of any kind may be offered for the donated embryos. Policies and procedures must be in place at the facility where the embryos were donated to ensure that neither donation nor refusal to donate affects quality of care received by the patient.[31]

There must also be a clear distinction between the donor's decision to create embryos for reproductive purposes, and the decision to donate embryos for research. This is ensured through a number of regulations which follow. First, the decision to create embryos for reproductive purposes must have been made without the influence of researchers proposing usage for the embryos to derive hESCs for research purposes. Consent for the donation of embryos should have been given at the time of donation. Finally, donors should have been informed that they have the right to withdraw consent at any time until derivation of stem cells from the embryo, or until the identity of the donor can no longer be linked to the embryo.[31]

When seeking consent from the donor, they must be informed of what will become of their donation. The donor must be informed that the embryonic stem cells would be derived from the embryos from research purposes. The donor must also be informed of the procedures that the embryo would undergo in the derivation process, and that the stem cell lines derived from the embryo may be kept for many years. In addition, the donors must be informed that the donation is not made with direction regarding the intended use of the derived stem cells, and the research is not intended to provide direct medical benefit to the donor. The donor is also to be informed that there may be commercial potential resulting from the research performed, and that the donor is not to benefit from commercial development as a result of the donation. The donor is also to be notified if information that could disclose their identity will be available to the researchers.[31]

Applicants seeking to use stem cell lines established before the effective date of the guidelines may use lines published on the NIH registry, or establish eligibility by complying with the requirements listed above. Alternately, researchers may submit materials to a working group of the Advisory Committee to the Director. The working group will review submitted materials and submit recommendations to the Advisory Committee, which will in turn make recommendations to the NIH director. A final decision regarding eligibility for funding is then made by the NIH director.[31]

The materials submitted to the working group must demonstrate that the stem cells were derived from embryos created for reproductive purposes, and are no longer needed. Also, the materials must demonstrate that the stem cells were donated by donors who had granted voluntary written consent.[31]

Research ineligible for NIH funding as dictated within the guidelines include research in which hESCs are introduced into non-human primate blastocysts. Research of the breeding of animals where hESCs may contribute to the germ line are similarly ineligible. NIH funding of the derivation of stem cells from human embryos is prohibited by the annual appropriations ban on the funding of human embryo research. Research using hESCs derived from other sources is also not eligible for funding.[31]

See the rest here:
Stem cell laws and policy in the United States - Wikipedia

Amanda is a retired educator with many years of experience teaching children of all ages and abilities in a wide range of contexts.

The cell membrane is a fluid, semi-permeable barrier which not only protects the interior of the cell but controls the movement of substances in and out.

William Cochot CC BY-SA 4.0 via Wikimedia Commons

Two main methods by which organisms move materials around inside their bodies are important for an understanding of cellular transport:

The movement of substances in and out of cells (nutrients in and toxins out, for example) is a very important part of biology as without it no cell and so no organism could live very long. Substances can only cross the protective cell membrane by diffusion, osmosis or active transport (don't worry - these terms will all be explained shortly). Mass flow only works at the organ, tissue and whole organism level.

You probably already know that all matter is made up of tiny, invisible atoms. When atoms become linked together, they form molecules. Both atoms and molecules can develop an electrical charge. Electrically charged atoms or molecules are called ions.

In biology, we use the simple term particles to refer to all of these things: atoms, molecules and ions.

It is these particles that move within and between cells by diffusion, osmosis or active transport. Particles can only be moved in out of cells when they are dissolved in water. Water with particles dissolved in it is known as a solution. The water in a solution is called the solvent and the particles are called the solute. We will come back to these terms later.

So that you can easily check your understanding, there's a fun quiz to do at the end. All the answers can be found on this page and you'll get your score straight-away.

The classic definition of diffusion is the movement of a substance from an area of higher concentration to an area of lower concentration (the concentration gradient). But what does that actually mean?

Particles are always in random motion. Concentration simply means how many particles there are in a given volume. By random motion, particles will naturally spread out from where there are lots of them to where there are few or none. This is what we mean by diffusion along the concentration gradient.

Watch this short animation to better understand this idea:

Two conditions must be met for a substance to enter a cell by diffusion.

Oxygen is an excellent example of a substance vital to life which enters cells by the process of diffusion. Oxygen is consumed by cells in the process of respiration. This means that the concentration of oxygen in any given cell is likely to decrease. This creates a concentration gradient which draws new oxygen into the cell by diffusion across the cell membrane.

The process of diffusion along a concentration gradient can also operate to move substances out of cells. An excellent example of this is the case of carbon dioxide. Carbon dioxide is a by-product of respiration. Consequently, carbon dioxide tends to increase in concentration in cells. Molecules of carbon dioxide exit the cell by diffusion once the concentration of the substance inside the cell is higher than it is outside the cell.

In both of these examples, the particles that make up the substance are moving down a concentration gradient: from an area of higher concentration to an area of lower concentration.

Diffusion in itself is generally a very slow process. Sometimes cells need to move substances more quickly and so a number of mechanisms have evolved to speed diffusion up.

These mechanisms use three key factors:

Let's look at each in turn.

You probably already know that when the temperature of a substance increases (it gets hotter) the particles that compose the substance start to move around a lot faster. This increase in movement when substances warm up can also help propel diffusion as the particles get going at a quicker rate.

Scientific Temperatures

In biology and the other sciences, temperature is always measured and expressed in C (degrees Celsius) and not in Fahrenheit, which you may be more familiar with at home.

Humans are "warm-blooded" animals or more properly, endotherms. This means that we can maintain a steady internal temperature. In our case this is about 37C and maintains our metabolism even when it is cold in the environment. All mammals are endothermic. Most reptiles, however, are exotherms, or "cold-blooded" and have to shut down if the environmental temperature falls below a certain level.

The larger a cell's surface area, quicker the movement of substances in and out. This is simply because there is more membrane for the substances to cross over. You can imagine the cell as a room, perhaps. If the doorway is wide, more people can walk in or out together. If the doorway is narrow, fewer people can come in and out at any one time.

But having a big surface area alone doesn't necessarily speed up diffusion. That large surface area has to be in a certain ratio to the internal volume of the cell. Sounds complicated? It does sound that way, but don't worry, it's actually fairly easy to grasp.

Being small and spherical helps cells to maintain a good volume to surface area ratio. Other adaptations include 'wobbly' membranes and flattening, all of which increase surface area and therefore the cell's ability to absorb substances by diffusion.

Ruth lawson CC BY-SA 3.0 via Wikimedia Commons

The most important factor for a cell is not just its surface area, but the surface area to volume ratio. The consumption rate of substances is dependent upon volume, but it is the cell membrane's surface area that determines the rate of absorption of new material.

In other words, the greater the surface area of the cell compared to its volume, the more efficient the cell will be in performing its functions.

It is interesting to note that as a cell gets bigger, its volume will increase more than its surface area. Let's look at what happens if you double the size of a cell:

So you can see that there is a negative relationship between size and efficiency in cells. The bigger they get the more difficult it is for them to take up materials fast enough.

There are three key ways by which a cell can increase its surface area to volume ratio.

Diffusion across the cell membrane happens because of the concentration gradient between the intracellular and extracellular environments.

Openstax Biology [CC BY-SA 4.0]

We have already seen that diffusion means the movement of substances from areas of high concentration to areas of low concentration.

However, the rate of diffusion is dependent upon the concentration gradient. The concentration gradient is calculated as the difference in concentration per centimeter.

Imagine a boy rolling a ball down a hill. If the hill is very steep, the ball will roll faster. If a concentration gradient is steep, that is to say it represents a rapid change from high concentration to low concentration, then substances will move down it faster - just like the ball!

A typical cell membrane is very thin. The reason for this is to keep the distance between internal and external concentrations short. This helps create a steeper concentration gradient, enabling the movement of substances in and out of the cell.

When you take a deep breath, the concentration of oxygen in the lungs is increased. The lungs are full of air with a high oxygen concentration compared to a lower oxygen concentration in the blood. Therefore, oxygen diffuses into the bloodstream.

The movement of substances in and out of the cell by diffusion is known as passive transport. However, sometimes substances will not diffuse across the membrane and need to be chemically assisted. This is known as active transport.

A typical situation in which active transport is required is when a substance must travel against the concentration gradient. Clearly in this case diffusion will not help at all!

Active transport always occurs across the cell membrane and it requires an input of extra energy to push the particles up the concentration gradient. The energy for active transport is provided by the process of respiration.

The cell membrane has specialised molecules incorporated into it. These carrier molecules absorb the energy of respiration in order to assist other substances in crossing the cell membrane.

Osmosis is exactly the same mechanism as diffusion but it is a term used to apply specifically to the movement of water molecules. So when water molecules (H2O) are transferred across a partially permeable membrane from an area of higher to an area of lower concentration, which is called osmosis.

Let's just pause here a moment to give some definitions of a few important terms we've used:

Something to think about...

Biologists will often refer to a solution which contains a large amount of solute as having a 'concentrated solution' but you can also think of that as a solution with a low concentration of water molecules. So the concept of high and low concentration is always relative to the molecules you are referring to!

An animal cell is surrounded by a partially permeable membrane. Because osmosis enables water to flow so freely through the cell system, it can do a lot of harm as well as good. The greatest danger is that of lysis.

A complex of chemical mechanisms ensures that, in a healthy animal, the tissue fluid surrounding the cells is maintained at an equal concentration to that of the cytoplasm.

Osmosis is far less of a threat to plant cells than to animal cells. In fact, they have evolved a rigid cell wall which enables them to use osmosis to their advantage.

Water enters a plant cell by osmosis when the cytoplasm has a lower concentration of water molecules than the surrounding aqueous environment. The cell expands to accommodate the influx of water molecules. This stretches the cell's wall. As we have seen with an animal cell, the membrane is not sufficiently strong to resist too much expansion and can burst, resulting in the cell's death. A plant's cell wall, however, is much stronger and as the cell fills with water, it exerts an opposite pressure until equilibrium is reached and no more water can enter. A plant cell in this state, full to capacity with water molecules, is called turgid.

This process is vital for plants. Turgid cells push tightly together and enable the plant to remain upright and hold its leaves towards the light.

When a plant wilts, or becomes flaccid, it is because of a lack of water. It can no longer absorb sufficient water molecules by osmosis to sustain its turgidity, so the leaves and possibly also the stem lose their main support.

If this condition is acute and prolonged, the vacuole in the plant cell's core, where water and nutrients are stored, can dry out, causing the cytoplasm to shrivel away. A plant in that condition is clearly dying. Its cells are referred to as being plasmolyzed.

Here is a bullet point summary of what we have learned on this page:

For each question, choose the best answer. The answer key is below.

If you got between 0 and 1 correct answer: A good attempt, but some revision might be worthwhile to improve your score.

If you got between 2 and 3 correct answers: You've grasped all the basics - well done! A bit of revision would help consolidate your knowledge.

If you got 4 correct answers: That's a great score - well done!

If you got 5 correct answers: Fantastic result! You have a good understanding of all the material. Excellent!

2015 Amanda Littlejohn

Amanda Littlejohn (author) on April 01, 2016:

Hi Alexis!

Thank you so much for your comment. Sorry it has taken me so long to reply, but I have only just received my notifications. Seems there was a glitch on some hubs.

I'm glad you enjoyed this biology article and I hope you find it useful for your son.

Bless you 🙂

Ashley Ferguson from Indiana/Chicagoland on February 18, 2016:

I loved biology as a child. Thank you for providing a child-friendly hub for my my son one day. 🙂 Hope to see you around in the hubs.

Amanda Littlejohn (author) on January 06, 2016:

Hi Shelley!

Thanks for your comment - I'm glad you enjoyed it. 🙂

FlourishAnyway from USA on December 06, 2015:

Excellent educational hub. Very thorough and well researched!

More here:
Biology for Kids: The Movement of Substances in and out of ...