cell-based products derived from cord blood, specically blood-forming stem cells (hemato­poietic progenitor cells), are FDA-approved for use in the country [136].

In 2017, the FDA introduced a comprehen­sive regenerative medicine policy framework through four guidance documents. These guide­lines were designed to support and accelerate the development of regenerative medicine products, including human cells, tissues, and cellular and tissue-based products (HCT/Ps). As part of this framework, the FDA imple­mented a 3-year period of risk-based enforce­ment discretion for specic HCT/Ps. This grace period allowed manufacturers to evaluate whether they needed to submit an investiga­tional new drug application (IND) or marketing application to the FDA or if they met the regu­latory criteria to continue marketing their prod­ucts under sect. 361 of the Public Health Service Act (PHSA), which does not require pre-market review and approval [137].

Since 2019, the FDA has issued over 350 “Warning Letters” and “Untitled Letters” to man­ufacturers, clinics, and healthcare providers regarding unapproved regenerative medicine products. Recent actions taken by the FDA, including citations, warning letters, product sei­zures, and even criminal charges, underscore the government’s heightened vigilance and commit­ment to regulating stem cell therapies [137].

necessitate organized follicular architecture, hair differentiation products, appropriate planar arrangement, and the ability to cycle and regener­ate. Subsequent endeavors should concentrate on developing more authentic and aesthetically pleasing models with potential clinical translation into therapies. Encouraged by novel ndings cen­tered on stem-cell-based therapies, efforts towards more effective treatments for hair loss are under­way. The secretome, a plethora of substances secreted by stem cells, garners increasing atten­tion for its pivotal role in regulating various physi­ological processes. While these initial strides are promising, there remains to be more clinical data to substantiate stem-cell-based therapies fully. Stem-cell transplants, conditioned media, and exosome therapies exhibit preclinical and some clinical success, albeit each carrying its own set of limitations requiring mitigation. It is imperative to note that hair follicle neogenesis is superuous for managing common alopecias (>97%) and would primarily nd relevance in rare follicular diseases, such as scarring alopecias or other con­ditions affecting the stem cell populations of the hair follicle (<3%).