Which of the following is NOT a strength of embryonic stem cells?

Embryonic stem cells are recognized for several key strengths that contribute to their potential in tissue engineering and regenerative medicine. These strengths include their unlimited self-renewal capability, which allows for the generation of a large number of stem cells over extended periods without losing their pluripotent characteristics. Additionally, they are found early in the embryo, specifically in the inner cell mass of the blastocyst stage, which is critical for their development into various cell types. Lastly, embryonic stem cells exhibit the highest level of pluripotency, meaning they can differentiate into any cell type in the body, which is essential for applications in tissue regeneration.

In terms of risk, while embryonic stem cells are a powerful tool, they are not inherently free from the infection risk posed by non-human pathogens. This is because the methods of deriving these cells may involve using animal products or encountering contamination during their cultivation. Thus, the presence of these risks can affect the safety and viability of using embryonic stem cells in clinical settings.

Therefore, the option indicating that embryonic stem cells are free of infection risk is not an accurate strength, underscoring why it is the correct answer to identify as not being one of their inherent strengths.