Dr. Jane Yoo, a board-certified dermatologist, breaks down how peptides, growth factors, and stem cell-derived ingredients work differently in skin. She uses a city repair analogy to explain their mechanisms and covers what's topical versus injectable, FDA approval status, and practical skincare applications.
Hi everyone, I'm Dr. Jane Yoo, board-certified dermatologist and Mohs surgeon. Today I want to break down the difference between stem cells, peptides, and growth factors. These terms are often mentioned together in skincare, but they are not interchangeable and serve very different roles in skin biology. Let's start with peptides. Peptides are short chains of amino acids, which are the building blocks of proteins like collagen and elastin. In skincare, peptides primarily act as signaling molecules. They tell skin cells what to do, such as stimulate collagen production, support the skin repair, or improve hydration. It's important to note, while some peptides are FDA-approved injectable medications for specific medical uses, such as hormone-related therapies like GLP-1 receptor agonists, injectable peptides marketed for cosmetic or anti-aging purposes are not FDA approved in the United States and should not be conflated with medical peptide drugs. There are different types of peptides used in skincare. Some peptides signal fibroblasts to help increase collagen production. Others slow collagen breakdown, support barrier function, or reduce muscle contraction to soften the appearance of expression lines. There are also carrier peptides that help deliver minerals involved in skin repair. Because peptides are relatively small, they tend to act in targeted and localized way when used topically and are generally well tolerated and are most appropriately used as part of a daily skincare routine rather than as injectable aesthetic treatments. Next are growth factors. Growth factors are larger, more complex proteins that function as messengers between cells. Their role is to signal skin cells to grow, divide, and repair. Growth factors are naturally present in the body and play a major role in wound healing and tissue regeneration, but their levels decline with age. In skincare, growth factors are used topically. Injectable growth factors for cosmetic use are not FDA approved in the United States. There are multiple types of growth factors, each with different functions. Some stimulate fibroblasts to produce collagen elastin, while others support epidermal renewal, and some help regulate inflammation and tissue repair. Because growth factors coordinate multiple cellular processes at once, their effects tend to be broader than those of peptides. Due to their size, growth factors primarily act through surface-level signaling rather than deep penetration, which is why Often they are used to support recovery after procedures rather than standalone corrective treatments. Now let's talk about stem cells, which are often the most misunderstood. Stem cells are unique cells capable of self-renewal and differentiation into specialized cell types in the body. In skincare, products do not contain live human stem cells. Instead, they typically contain stem cell-derived ingredients, most commonly plant stem cell extracts or lab-cultured derivatives. Rather, they provide antioxidant production and signaling molecules that help support skin resilience and improve how the skin responds to aging and environmental stress. Plant-derived stem cell extracts are used for their protective properties, not because they replace or regenerate human tissue. Different sources of stem cell-related ingredients may vary in composition, but their role in skincare is supportive rather than regenerative. A helpful way to think about this is to imagine your skin as a city undergoing maintenance and repair. Peptides are like individual text messages sent to specific workers telling them to patch a crack, reinforce a wall, or improve hydration in a particular area. Growth factors act more like citywide announcements. They coordinate larger repair efforts, signaling multiple teams to regenerate tissue, produce collagen, and heal damage. Stem cell-derived ingredients help support the city itself, but they don't replace buildings or create new structures. They help protect the environment, reduce damage from stress, and support the systems that allow repair to happen more efficiently. Each plays a different role, and none of them do the same job. So, understanding these differences matters because each plays a distinctive role, and they are most effective when used appropriately rather than interchangeably.
