KGF Research History: Discovery, Key Trials and Regulatory Timeline

Keratinocyte growth factor (KGF) is the name given to a fibroblast-secreted protein that acts on epithelial cells, and which was subsequently numbered fibroblast growth factor 7 (FGF7) within the FGF family. A 2024 primer on FGF7 summarised the molecule's nomenclature, its paracrine mesenchyme-to-epithelium mode of action, and its signalling through an epithelial-restricted FGF receptor splice variant, and described how the factor's biology has been studied across tissues (PMID 39048474). This page traces how that record was assembled: the discovery period, the main research threads in chronological order, and the regulatory milestones for the recombinant product as published. It states no doses, makes no efficacy claims and gives no use guidance.

Before the molecule had a name

Part of the pre-history of KGF belongs to developmental lung biology, where investigators described a mesenchyme-derived activity, fibroblast-pneumocyte factor, that appeared to relay hormonal signals from fibroblasts to alveolar epithelium. A 2016 paper revisited that long-standing question and asked what the identity of fibroblast-pneumocyte factor actually is, reviewing candidate fibroblast-derived mediators against the original observations (PMID 27500537). The paper is useful historically because it illustrates the research problem that KGF's identification helped address: biologists had functional evidence of fibroblast-to-epithelium signalling well before the individual proteins carrying that signal were cloned and named.

Discovery and naming

Reviews place the identification of KGF in the late 1980s, when it was characterised as a factor secreted by fibroblasts and mitogenic for epithelial cells rather than for the fibroblasts producing it; it was later catalogued as FGF7 within the fibroblast growth factor family, and the 2024 primer treated both names as referring to the same protein (PMID 39048474). That same primer described the target-cell selectivity that distinguishes FGF7 from most other FGFs, its receptor preference restricts activity largely to epithelial compartments, which is the property that shaped nearly every research programme that followed (PMID 39048474).

Chronological timeline of the published record

Research thread 1: epithelial-mesenchymal signalling

The earliest and most durable thread concerns how connective-tissue cells instruct the epithelium above them. The 2024 FGF7 primer framed this directly, describing FGF7 as a paracrine mediator released by mesenchymal cells and read by epithelial receptors, with roles across development, wound repair and tissue homeostasis (PMID 39048474). Parallel tissue-specific reviews populated the same concept in individual organs: a 2001 review of the human ocular surface described the maintenance of corneal and conjunctival epithelium and its dependence on underlying stromal signalling (PMID 11470454), and a 2008 study built tissue-engineered models of oral dysplasia in which engineered epithelium was grown with a fibroblast-containing connective-tissue compartment to study abnormal epithelial behaviour (PMID 18484684). Taken together, these papers show why an epithelial-selective growth factor attracted attention across ophthalmology, oral pathology and lung development rather than in one speciality alone (PMID 39048474, PMID 11470454).

Research thread 2: mucosal injury and the recombinant product

The clinical development path that produced a licensed KGF product ran through chemotherapy- and radiotherapy-associated oral mucositis, where the injured target is squamous epithelium. Regulatory records list the recombinant truncated human KGF, palifermin, as approved in the United States in 2004 for severe oral mucositis in patients with haematologic malignancies receiving myelotoxic therapy requiring haematopoietic stem cell support, with European authorisation following in 2005; reviews of thymic regeneration subsequently referred to KGF/palifermin as an agent that had already moved from preclinical work into clinical use (PMID 27088907). That regulatory status matters for reading the later literature: once a recombinant KGF product existed, reviews in other fields could discuss it as an available investigational tool rather than a purely laboratory reagent (PMID 37659170). This page does not reproduce prescribing information, indications in individual jurisdictions or product labelling.

Research thread 3: thymus, immune reconstitution and later reviews

The most active recent KGF thread sits in immunology. A 2016 review of thymic regeneration surveyed approaches aimed at restoring thymic epithelial cells after injury or age-related involution and placed KGF among the strategies researchers had examined for supporting the thymic epithelial compartment (PMID 27088907). A 2023 review of thymus aging and immune reconstitution revisited the same territory, summarising progress and the remaining obstacles in restoring T-cell output after cytoreductive therapy or with age (PMID 37659170). A later review on thymic regeneration in the context of tumour immunotherapy continued that line, discussing why thymic recovery is a limiting factor for reconstituting a diverse T-cell repertoire (PMID 42712902). Across these reviews the authors described the field as still preclinical or exploratory for most regenerative strategies rather than settled (PMID 37659170, PMID 42712902).

Research thread 4: skin, hair follicle and pigmentation literature

Dermatology supplied a separate set of fibroblast-to-epithelium questions. A 2017 paper examined the precise role of dermal fibroblasts in melanocyte pigmentation, reporting that fibroblast-derived mediators influence melanocyte behaviour in the overlying epidermis (PMID 28711237), and a 2020 comprehensive review on the emerging role of the dermal compartment in skin pigmentation drew the same conclusion across a wider body of work, arguing that pigmentation is regulated from below as well as within the epidermis (PMID 32243635). In hair research, a 2024 review compared plant extracts studied for hair loss and hair growth and catalogued their phytochemical components and the growth-factor and signalling targets those extracts were reported to modulate in follicle biology (PMID 38792149). These dermatology papers are background to KGF rather than KGF trials, and none of them reported outcome data for a KGF product (PMID 32243635, PMID 38792149).

Research thread 5: KGF as a disease biomarker

A fifth strand treated KGF not as an intervention but as a measurable marker. A 2022 systematic review on the endotyping of cholesteatoma asked which molecular biomarkers had been reported across the published studies of this keratinising middle-ear disease and assembled the candidate marker set, which included growth factors involved in keratinocyte proliferation (PMID 36013295). The study illustrates a general pattern in the KGF record: the same molecule appears as a candidate driver, a candidate biomarker and a candidate therapeutic target depending on the tissue under study (PMID 36013295).

Adverse Events in the Cited Literature: What Studies Report

The papers verified for this page are primarily reviews, primers, systematic reviews and laboratory models, and they were not designed as safety studies. The 2016 and 2023 thymus reviews discussed regenerative strategies and the challenges of immune reconstitution without presenting pooled adverse-event tabulations for individual agents (PMID 27088907, PMID 37659170), and the 2024 FGF7 primer addressed molecular and tissue biology rather than clinical tolerability (PMID 39048474). Readers looking for safety information on the approved recombinant product should consult that product's approved labelling and regulatory assessment reports, which are the documents that carry adverse-event data. No adverse-event frequencies are stated here because the verified set does not supply them.

How to read this history

• Two names, one protein. KGF and FGF7 refer to the same factor, as the 2024 primer set out (PMID 39048474).
• Approval is narrow. A licensed recombinant KGF product exists for a defined oncology-supportive-care setting; reviews outside that setting described KGF-based approaches as investigational (PMID 27088907, PMID 42712902).
• Most tissue literature is mechanistic. Ocular surface, oral mucosa, pigmentation and hair papers describe biology and models, not KGF outcome trials (PMID 11470454, PMID 18484684, PMID 28711237).
• Research-grade material is not a medicine. Peptides and proteins supplied for laboratory work are labelled research use only and are regulated differently from approved products.

A general overview of KGF biology, nomenclature and the current evidence base is kept separately at /learn/kgf/ on this site.

This page is for educational purposes only and is not medical advice; consult a licensed physician about any medical question, and do not use research compounds outside an authorised research or clinical setting. It summarises published literature only and is not legal or regulatory advice.

References

• Primer on fibroblast growth factor 7 (FGF 7) (Differentiation, 2024)
• What is the identity of fibroblast-pneumocyte factor? (Pediatric Research, 2016)
• Thymus: the next (re)generation (Immunological Reviews, 2016)
• Thymus aging and immune reconstitution, progresses and challenges (Seminars in Immunology, 2023)
• Thymic regeneration and tumor immunotherapy (Frontiers in Immunology, 2026)
• Characteristics of the human ocular surface epithelium (Progress in Retinal and Eye Research, 2001)
• Tissue engineering of oral dysplasia (The Journal of Pathology, 2008)
• Precise role of dermal fibroblasts on melanocyte pigmentation (Journal of Dermatological Science, 2017)
• Emerging role of dermal compartment in skin pigmentation: comprehensive review (JEADV, 2020)
• Can Plant Extracts Help Prevent Hair Loss or Promote Hair Growth? (Molecules, 2024)
• Endotyping of Cholesteatoma: Which Molecular Biomarkers? A Systematic Review (Journal of Personalized Medicine, 2022)