Stem Cell Basics #1 (By Danielle L. King)

Human Lungs isolated. X-Ray effectHannah Warren, a 2-year old girl born without a trachea made recent news for receiving a synthetic windpipe generated from her own stem cells. The stem cells were taken from Hannah’s bone marrow and placed onto an artificial scaffold, where the stem cells divided and replicated themselves into a new windpipe. Hannah survived 3 months with a normally functioning trachea succumbing to problems with other organs that could not be replaced. This is just one of many cases of the use of stem cells in modern medicine.

What are stem cells?

Stem cells are relatively unspecialized cells that have the ability to develop and differentiate into different cell types with a specific function. In other words, they are not devoted to a specific function, however they have the potential to differentiate into a specialized cell. Stem cells work to renew and restore cells in specific tissues and organs, by means of cell division. The division of a stem cell can result in an undifferentiated stem cell or a specialized cell. These specialized cells can be used towards further understanding of infections, cancer and many other diseases. In addition stem cells can aid in the study of new drugs and are the forefront in the future of tissue engineering and regenerative medicine, as displayed in the case of Hannah’s windpipe.

Types of Stem Cells:

There are two main sources of stem cells, which are embryonic stem cells and non-embryonic (also known as somatic, tissue, or adult stem cells). Embryonic stem cells are cells derived from an embryo that can differentiate into all specialized cells of the body. Non-embryonic stem cells are undifferentiated cells derived from a tissue or organ with the ability to differentiate into specialized cells for that specific tissue or organ. Owing to the fact embryonic stem cells can produce any type of cell in the body, they have a greater potency than adult stem cells. Thus, the potential for a stem cell to differentiate into a specialized cell varies. Therefore, stem cells are categorized into groups based on their capability to specialize, which is listed as follows: totipotent, pluripotent, multipotent, oligopotent and unipotent.


Stem Cell Sources:

Stem cells can be taken from specific sources in the body:

-Bone Marrow

-Peripheral Blood

-Umbilical Cord Blood and Tissue

-Tissue Stem Cells


-Adipose Tissue




1. Fitzgerald, Kelly. “Two-Year-Old Girl Born Without A Windpipe Receives Artificial

Trachea Grown From Stem Cells.” . N.p., 2 May 2013. Web. . <>.

2. Stöppler, Melissa. “Stem Cells.” . Medicine Net Inc., 13 July 2014. Web. .


3. “Stem Cell Information.” National Institutes of Health. National Institutes of Health, 04

Apr 2013. Web. <;.

4. “What are stem cells.” CHXA. CHXA, n.d. Web. <





Threats to Male Fertility: Pesticides

farmer spraying pesticide in the rice fieldIf you have read our previous blogs, you know that some plastic chemicals and recreational drugs are threats to male fertility. These gonadotoxins either directly affect the testes or affect the hormones that produce sperm. Chemicals in pesticides have been shown to impact male fertility, though recent articles have suggested more research needs to be done in this area.

Effects of Pesticides

Since the early 2000s, the majority of studies linking male infertility to pesticides have reported that pesticide exposure leads to poor sperm quality and reduced sperm concentrations.1 Clear effects on sperm quality, for example, have been demonstrated for dibromochloropropane (DBCP) and ethylene dibromide, the active ingredients in some agricultural fumigants.2 Not all pesticides are so clear-cut, though. One article in particular notes that many of these studies are inconsistent, citing problems with sample populations, pesticide exposure, and study design.1

Research published as recently as 2011, however, strengthens the connection between pesticides and infertility. Scientists at the University of London tested 34 widely-used pesticides with high exposures through diet and found that 23 of them reduced fertility. The researchers recommend additional testing, but the study again points to the negative effect of pesticide exposure on fertility.3


In many cases, gonadotoxic effects are reversible once exposure to the pesticide is eliminated, but because there are hundreds of pesticides, it can be difficult and even impossible to know exactly which one may be impacting your fertility. Still, there are some measures you can take to reduce exposure:

  • Thoroughly wash produce before eating, as many pesticides and fungicides used on agricultural crops contain gonadotoxins.
  • Limit exposure to wood preservatives and industrial chemical applications, if possible.

If you think pesticides might be the reason for your infertility, you should talk to your doctor about possible treatments.


  1. Roeleveld, N., & Bretveld, R. (2008, June). The impact of pesticides on male fertility. Curr Opin Obstet Gynecol, 20(3), 229–33. Retrieved from
  2. Bretveld, R., Brouwers, M., Ebisch, I., & Roeleveld, N. (2007, February). Influence of pesticides on male fertility. Scand J Work Environ Health, 33(1), 13–28. Retrieved from
  3. Tal, T. (2011, May 17). Widely used but just tested pesticides may contribute to infertility. Environmental Health News. Retrieved from


Threats to Male Fertility: Recreational Drugs

In a previous postDrugFreeZone, we talked about what gonadotoxins are and how chemicals found in everyday plastics can impact male fertility. But plastic chemicals aren’t the only toxins out there affecting sperm production. Drugs, such as nicotine, alcohol, marijuana, and steroids are common substances that can negatively impact fertility.

Recreational Drug Use

When you consider fertility, sperm count is not the only number that matters. Sperm quality, such as the size and shape of the sperm and the quality of the DNA they carry, are also factors that have been linked to male infertility. These recreational drugs may affect your fertility, especially if you are struggling with infertility. Here’s a list of common drugs and their known effects on fertility:

  • Tobacco smoke: Lowers sperm count among men who smoke and possibly men who breathe secondhand smoke.
  • Alcohol: Lowers testosterone levels, causes erectile dysfunction, and decreases sperm production. Liver disease caused by excessive drinking may lead to fertility problems as well.
  • Cocaine and marijuana: May temporarily reduce the number and quality of sperm.Long-term use of marijuana may result in low sperm count and abnormally-developed sperm.
  • Steroids: Anabolic steroids taken to stimulate muscle strength can cause the testicles to shrink and sperm production to significantly decrease.


If you think recreational drug use might be the reason for your infertility, you should talk to your doctor about possible treatments. In many cases, gonadotoxic effects are reversible once exposure to the toxin is eliminated (in this case, once recreational drugs use has ceased). Your doctor may, however, recommend additional treatments, to help improve these and additional adverse effects of recreational drugs such as erectile dysfunction, or decreased testosterone, among others.



Threats to Male Fertility: Plastics

Environmental contaminationA gonadotoxin is a chemical or substance that affects sperm production by the testis….one of several threats to male fertility. You may have heard this term in relation to cancer treatment or prescription medications, but the doctor’s office is not the only place to run across gonadotoxic agents. There are things you interact with every day that may bring you into contact with chemicals that have a negative impact on your fertility.

Two studies published this year indicate that phthalates, a common ingredient in many plastics, contribute to male infertility.1 In the first study, published in Fertility and Sterility, male exposure to the chemical was associated with an approximately 20% reduction in fertility.2 The second study, published in Environmental Science and Pollution Research, indicates why there might be such a reduction: Exposure to phthalates correlates with a significant decrease in sperm motility and sperm concentration. Additionally, phthalates seem to contribute to DNA damage and may influence the reproductive hormone testosterone.3

What and Where are Phthalates?

Phthalates (pronounced THA-lates) are a group of chemicals often called plasticizers because they are used to make plastics more flexible and difficult to break; polyvinyl chloride (PVC) plastics are a common source. They are also used as dissolving agents for other materials. This is just a short list of the kinds of products that often use phthalates:4

  • plastic packaging
  • garden hoses
  • inflatable toys
  • medical tubing
  • vinyl flooring
  • adhesives
  • detergents
  • lubricating oils
  • automotive plastics
  • plastic clothes, such as raincoats
  • personal-care products, such as soaps, shampoos, hairsprays, and perfumes2

Because phthalates aren’t chemically connected with plastics, they can leach out of the products that contain them, and direct contact with these products exposes a person to the leached chemical.5

What Can I Do to Avoid Phthalates?

Although the authors of the second study point out that their small sample size limits the findings of their report, the fact that these two studies were conducted and published separately indicates that there may be some cause for concern. Below are some suggestions for reducing your exposure to phthalates:5

  • Use alternatives to PVC plastics whenever possible.
  • Use glass containers for storing food whenever possible, or choose plastic containers that aren’t manufactured with phthalates. Plastic products with recycling codes 3 and 7 may contain phthalates or BPA. Look for plastic with recycling codes 1, 2, or 5. Refer to the American Chemistry Council for a description of recycling codes and plastics used in packaging.
  • When in doubt about the type of plastic you are using, ask the manufacturer whether their product contain phthalates.
  • Check the ingredients of any personal-care products you use, such as soaps, shampoos, hairsprays, and perfumes; these products should be labeled with their ingredients. For example, dibutyl phthalate and diethyl phthalate are two phthalates you might commonly see in an ingredient list.


  1. Jones, B. (2014, May 18). Male infertility may partially result from chemicals in plastic. Liberty Voice. Retrieved from
  2. Louis, G., Sundaram, R., Sweeney, A., Schisterman, E., Maisog, J., & Kannan, K. (2014, February 17). Urinary bisphenol A, phthalates, and couple fecundity: The Longitudinal Investigation of Fertility and the Environment (LIFE) Study. Fertility and Sterility, 101(5), 1359–1366. Retrieved from
  3. Pant, N., Kumar, G., Upadhyay, A., Patel, D., Gupta, Y., & Chaturvedi, P. (2014). Reproductive toxicity of lead, cadmium, and phthalate exposure in men. Environmental Science and Pollution Research. Retrieved from
  4. CDC. (2013, July 16). Factsheet: Phthalates. Retrieved from
  5. Canadian Cancer Society (n.d.). Phthalates. Retrieved from


Andropause: Should I be worried?

Young, sad man deep in thought, troubled by bad newsAfter age 30, men begin to produce decreased levels of androgen, or the hormones that control the development and maintenance of male sex organs and secondary sex characteristics, such as facial hair, increased muscle mass, and low percentage of body fat. This aging is often compared to menopause in women and is commonly referred to as “andropause.” Some scientists, however, more appropriately use the term “androgen decline in the aging male,” or ADAM.1

Unlike menopause, ADAM is a slowly progressive condition, and it is somewhat difficult to diagnose because there is disagreement about what the normal level of testosterone is for any given patient. Additionally, many symptoms may indicate the presence of other disorders or diseases, such as diabetes or high blood pressure, or medications.2 Still, researchers have noticed links between low androgen levels and abnormal health.3

Testosterone’s Role

The most well-known androgen is testosterone, and when it is on the decline, there are several adverse health effects.2

Physiological changes include:

  • diminished libido, sexual activity, and erections
  • decreased lean body mass and increased fat
  • reduced muscle strength
  • reduced energy
  • osteoporosis
  • lower quality of sleep

Psychological and cognitive changes include:

  • mood changes and depression
  • reduced cognitive function
  • reduced sense of well-being

Testosterone Therapy

Although there have been no long-term studies conducted to determine prolonged safety, several clinical studies have shown supplemental testosterone, or testosterone replacement therapy, to be beneficial and safe, alleviating symptoms and sometimes even reversing them.2 However, testosterone supplementation is not without its own concerns4.

If you are experiencing any of these physiological, psychological, or cognitive symptoms, you may want to talk to your doctor about testosterone therapy. If a blood test confirms a low testosterone level, you can choose one of a number of testosterone treatments, depending on individual benefits, side effects, and cost. Treatments include oral tablets, injections, subcutaneous implants, skin patches, or topical gels.5

One thing to keep in mind, however, is that testosterone therapy is not advised for men who have or have had prostate cancer or breast cancer. Associations between testosterone therapy and prostate health are being studied, so it is important to talk with your doctor about the potential benefits and risks of treatment.6


  1. Morales, A., Heaton, J., & Carson, C. (2000). Andropause: A misnomer for a true clinical entity. The Journal of Urology163(3), 705–712. Retrieved from
  2. Brawer, M. (2004). Testosterone replacement in men with andropause: An overview. Reviews in Urology, 6(Suppl. 6), S9–S15. Retrieved from
  3. Testosterone and the aging male – Balancing risks and benefits
  4. WebMD (n.d.). Low testosterone and your health. Retrieved from
  5. WebMD (n.d.). Erectile dysfunction: Testosterone replacement therapy. Retrieved from
  6. WebMD (n.d.). Low testosterone: How do you know when levels are too low? Retrieved from