Growth Factors

Growth factors are proteins the body uses to instruct cells. They bind to receptors on a cell surface and trigger a response: divide, migrate, or produce a particular protein. In skin, certain growth factors instruct fibroblasts in the dermis to produce collagen and elastin.

What the sh- prefix means

It stands for synthetic human. These are peptides whose amino acid sequences match human proteins, manufactured through fermentation using engineered yeast or bacteria. No human tissue is involved and none is present in the product.

The naming distinguishes sequence from source. A sequence identical to a human protein, produced in a fermentation tank, is a different thing from material derived from human cells, and the INCI system reflects that.

Which proteins these correspond to

Each number maps to a specific characterised protein:

• sh-Oligopeptide-1 corresponds to epidermal growth factor, EGF, which acts on keratinocytes in the epidermis
• sh-Polypeptide-1 corresponds to basic fibroblast growth factor, bFGF, which acts on fibroblasts in the dermis
• sh-Polypeptide-11 corresponds to insulin-like growth factor 1, IGF-1

The biology of these proteins is well established. Their behaviour applied to intact skin is a separate question.

The delivery problem

This is the honest limitation of the entire category and it applies to every brand selling growth factors.

Growth factors are large. Depending on the specific protein, they run from roughly 6,000 to over 25,000 daltons. The stratum corneum is structured to exclude molecules much above 500 daltons.

So the central question is whether meaningful quantities of intact growth factor reach the fibroblasts they are meant to signal. Formulators use liposomes, phospholipid carriers and other delivery systems to address this, and studies do report measurable improvements in appearance. But appearance can improve through hydration, film formation or barrier support without any growth factor reaching the dermis at all. A positive result does not by itself confirm the proposed mechanism.

Where the evidence is strongest

Growth factors have well-documented roles in wound healing, where the barrier is already breached and delivery is not in question. Much of the enthusiasm for topical growth factors originates there. Extrapolating from wounded to intact skin is the step that remains uncertain.

The safety question

Growth factors promote cell proliferation. That is their function.

Some dermatologists have raised a theoretical concern about their use in people with a history of skin cancer, on the reasoning that a proliferative signal is not obviously desirable where abnormal cells may be present.

No evidence of harm has been demonstrated, and delivery limitations arguably make the concern less pressing than it sounds. But it is a genuine discussion in the field rather than an invented worry, and it belongs in a conversation with your doctor rather than being resolved by a product page.

Reading the label

Position in the ingredient list is informative. Growth factors are used at very low concentrations, and appearing near the end of a long list is normal rather than a red flag. What the label cannot tell you is the delivery system, which matters more here than in almost any other category.