Research progress and strategies for the biosynthesis of keratinocyte growth factor-2 (KGF-2) in Arabidopsis thaliana

KGF-2 in skin wound healing

Wound healing is a complex physiological process, which can be divided into the inflammatory phase, proliferative phase, and remodeling phase (Xiaojie et al., 2022). Each of these phases requires intricate coordination to avoid exorbitant activation, which leads to faulty healing. During the inflammatory phase, KGF-2 regulates the inflammatory response and inhibits the overexpression of inflammatory factors (Braun et al., 2004). During the proliferative phase, KGF-2, via its FGF receptor 2 IIIb (FGFR2 IIIb) signaling, has been shown to play a vital role in skin wound healing where it not only promotes the proliferation of keratinocytes but also regulates the phases of tissue healing (Chen et al., 2009; He et al., 2024; Fang, Bai & Wang, 2010). During the remodeling phase, KGF-2 inhibits STAP-2 expression and signal transducer and activator of transcription 3 activation, resulting in a significant reduction in collagen I and III levels, thereby reducing scar formation while facilitating wound healing (Zhou et al., 2022). Smith et al. (2000) found that KGF-2 significantly increased the interstitial closure rate of human meshed skin graft on a “nude” rat model, significantly promoting wound healing. Observations by Gao et al. (2021) also showed that pretreatment of the epidermis with KGF-2 mitigates the degree of skin photodamage by inhibiting cell apoptosis, reducing oxidative stress and regulating AhR/Nrf2 signaling pathway, which in turn prevents DNA damage and mitochondrial dysfunction. Taken together, these findings indicate that KGF-2 facilitates wound healing while reducing scar formation making it a potential anti-scarring therapeutic.

KGF-2 in eye injury repair

Corneal injury is a lesion caused by either trauma or exposure to external stimuli, that disrupts the corneal epithelium leading to symptoms such as pain, burning, and tearing of the eye. The process of corneal injury repair can be divided into the lag or latent, migration, proliferation and differentiation, and the reattachment and matrix remodeling phase. In the initial stages of the process, inflammatory cells migrate to the wound site causing inflammation, redness, swelling, and blurred vision. Naive epithelial cells then migrate to the wound site, proliferate and differentiate to form a new epithelial layer that seals the wound site, gradually leading to healing. Complications such as microbial infection or ulcer formation may affect the outcome of corneal healing as they can lead to loss of corneal transparency. The role of KGF-2 in corneal injury repair has been explored using various models. KGF-2 promotes the proliferation and differentiation of epithelial cells, promotes epidermal regeneration, and accelerates corneal wound healing. Yang, Fu & Li (2002) showed that in chronic wounds of adults, KGF-2 accelerates wound closure faster than EGF as its promotion of keratinocyte proliferation is significantly higher. Using the rat corneal alkali burn model, Cai et al. (2019) compared the efficacy of bFGF and KGF-2 in preventing excessive wound healing and scar formation. Observations from this study showed that KGF-2 is a significantly better facilitator of epidermal regeneration, migration, and scar formation reduction, thus suggesting it can be used to treat corneal injury. Similarly, Ergen et al. (2022) showed that KGF-2 effectively improves early reepithelialization, opacification, and neovascularization while reducing inflammation in corneal alkali burn. Subsequent related studies also showed that KGF-2 stimulates limbal epithelial stem cells to migrate to the central cornea, thus, accelerating the healing of alkali burn cornea (Liu et al., 2005). KGF-2 activates and regulates p38, ERK1/2, Nrf2 and P13K signaling pathways to promote the repair of corneal injury (Xiaojie et al., 2022). KGF-2 could induce cell proliferation and migration by activating ERK1/2 and p38 signaling pathways (Cai et al., 2019). Liu et al. (2022) have shown that KGF-2 can prevent cataracts by regulating Nrf2/hydroxide ion and PI3K/Akt pathways, eliminating oxidative stress and apoptosis induced by hydrogen peroxide (hydrogen peroxide monovalent anion) in human lens epithelial cells (HLECs) and rat lenses.

KGF-2 in promoting hair regeneration

Hair is not just a defining characteristic of mammals but is also regarded as a natural ornament, hence, it plays an important role in personal appearance and perception. Hair also confers other protective functions, such as protecting the scalp from ultraviolet rays, low temperature, and external factors. Hair growth is a complex cyclic and periodically controlled process characterized by rapid growth (anagen), regression (catagen), and resting periods (telogen) (Liu et al., 2016). This process is regulated by many factors, such as genetics, nutrition, environmental factors, hormones, and individual health status. Hair follicles are composed of epidermal and dermal (mesenchymal) compartments, whose interaction is essential for the maintenance of the morphology and growth of hair follicles. At the bottom of hair follicles are dermal cells surrounded by the hair matrix (HM), which induce and regulate hair growth by modulating signals across the entire hair follicle epithelium. These dermal cells are also known to release growth factors, such as insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF), which also influences hair growth (Itami, Kurata & Takayasu, 1995; Lachgar et al., 1999). Other growth factors have also been demonstrated to influence hair growth. For example, KGF and hepatocyte growth factor (HGF) have stimulatory effects on hair follicle growth while EGF and transforming growth factorβ-(TGF-β) have inhibitory effects on hair follicle growth (Roh et al., 2002; Lichtenberger, Mastrogiannaki & Watt, 2016). Among the members of the FGF family, FGF-10 is known to significantly promote hair growth (Xiaojie et al., 2022). In wound healing, FGF-10 promotes hair follicle cell proliferation and migration and induces anagen. Similar observations have been made in nude mice where FGF-10 binds FGFR2IIIb to increase and grow hair follicles in nude mice (Petiot et al., 2003). The regulation of hair follicle morphological development and cycles involves a variety of different molecular signaling pathways, mainly including Wnt/β-catenin signaling pathway, sonic hedgehog (SHH) signaling pathway, Notch signaling pathway and so on Wang et al. (2022). Wingless/Integrated (WNT) signaling protein is mainly expressed during hair follicle anagen, decreased during catagen, and inactivated during telogen (Lin, Zhu & He, 2022). SHH is a small secreted glycoprotein, that is involved in the regulation of follicle cycling and promotes the transition of hair follicles from telogen to anagen (Gao et al., 2019). KGF-2 can regulate hair follicle development by activating Wnt/β-catenin and SHH signaling pathways. A recent study by Zhang et al. (2018) showed that FGF-10 and frizzled-related protein 1(sFRP1) compete to regulate the development of hair follicles. In the study, FGF-10 was shown to promote hair growth and regeneration by increasing the nuclear levels of β-catenin (Zhang et al., 2018). Jang (2005) found that the application of recombinant human KGF-2 (rhKGF-2) can significantly stimulate the proliferation of human hair follicle cells (26–35 perent). Among all commercial FGFs approved by the State Food and Drug Administration (SFDA) for wound healing, KGF-2 is the best candidate for stimulating hair growth of hair follicles at the wound site (Xiaojie et al., 2022). KGF-2 has the highest rate of hair growth stimulation compared with FGF-1 and FGF-2 (Lin et al., 2015). While FGF-1 and FGF-2 are capable of inducing hair growth, the induction of hair growth is delayed, ununiform, and only occurs at proximal regions. Mice treated with KGF-2 show a more uniform hair growth with longer hair length (Lin et al., 2015). At the same time, related studies have shown that KGF-2 can induce hair growth by up-regulating the expression of Wnt/β-catenin and sonic hedgehog (SHH), and this up-regulation begins to decrease at 3 and 4 weeks, leading to the end of hair follicle growth phase. Continuous stimulation keeps the hair follicles in the growth phase, which may lead to the development of hair follicles in the direction of tumors (Lin et al., 2015). The poor transdermal absorption properties of KGF-2 impede its promotion of hair regeneration. To overcome this limitation, recombinant KGF-2 have been fused to other molecules with better transdermal properties. Li et al. (2017) fused rhFGF-10 to an oil body gene, oleosin-rhFGF-10 protein, and this enhanced the protein’s stability and effect. Liu et al. (2016) used the dimer oil-globulin fusion method to express KGF-2 and verified its biological activity, and found that KGF-2 could be expressed by this method, and the asymmetric O-O:: KGF-2 construct had the highest expression and biological activity. Compared with recombinant FGF-10 expressed in prokaryotic systems, recombinant FGF-10 (oleosin-rhFGF-10) expressed in plants (such as safflower) is more effective in promoting skin wound healing and hair growth in mice (Li et al., 2017).

KGF-2 fusion expression strategy

Although KGF-2 plays an important role in hair growth, wound healing, and embryonic development, its short half-life, poor thermal stability, and low transdermal properties limit its potential clinical application, especially in tropical regions. At the same time, the production of KGF-2 faces the problems of low expression, high cost, insufficient post-translational modification, and complex technology. To overcome these limitations, various methods of expressing and modifying KGF-2 have been employed. For example, hKGF-2, containing 208 nucleic acids, has been subcloned into pET-30a(+) and successfully expressed in a prokaryotic system, the yield was approximately 2.2 g/L (Kim et al., 2023). To improve its solubility, FGF-10 can be fused with the Halo-tag and expressed (Sun et al., 2015). Full-length hFGF-10 has also been subcloned into pPICZα and expressed in Pichia pastoris GS115, the yield was approximately 1.0 g/L (Giddings et al., 2000). The acquired rhFGF-10 was shown to promote the proliferation of NIH-3T3 (Giddings et al., 2000). Although the rhFGF-10 showed similar biological functions to those of natural FGF-10, modified FGF-10 is still prone to denaturation. Thus, needing further modification to increase stability. The fusion of oil body-protein or dimeric oil-globulin fusion has been shown to reduce protein denaturation. Furthermore, the fusion of a protein to an oil body increases its transdermal properties. Some researchers used oil body-protein system and dimeric oil-globulin fusion method to express KGF-2, and used plant bioreactors to obtain bioactive KGF-2 (Liu et al., 2016; Li et al., 2017). Construct a plant expression vector containing the KGF-2 gene, combined with the oleosingene or other genes, and then transfer the vector into Agrobacterium tumefaciens. Seeds were screened after transforming plants using the floral dip technique. T3 seeds were screened to obtain the single copy homozygous generation. These methods can enhance the stability of the expressed protein, which is conducive to long-term expression and application; moreover, the transdermal ability of KGF-2 combined with oil body is also enhanced compared with that of KGF-2 expressed in prokaryotic system (Liu et al., 2016; Li et al., 2017). KGF-2 has been expressed in prokaryotic expression systems, yeast expression systems and plant expression systems. Different expression systems have different advantages and disadvantages for expressing foreign proteins. Table 1 presents the potential advantages and disadvantages of KGF-2 expression by different expression systems (dos Santos et al., 2024; Liu et al., 2016; Li et al., 2017; Kim et al., 2023; Sun et al., 2015; Giddings et al., 2000).

Taken together, the use of a fusion strategy to express KGF-2 can increase its half-life and solubility without affecting its biological activity and this may lead to increased clinical efficacy and application.

Skin is the largest organ of the human body, which constructs the first barrier of the body’s defense (Zhang et al., 2021). Due to the existence of the skin barrier, most biological macromolecules are unable to effectively penetrate the skin barrier. This not only hinders the penetration of harmful substances but also of drugs making them less effective (Hänel et al., 2013). Various transdermal drug delivery systems have been used to increase the penetration of drugs across the skin barrier, and the right delivery system or method can make active ingredients such as drugs work better (Zhang et al., 2021). Transdermal delivery methods can be divided into physical, chemical, or biological methods. Physical methods include electroporation, microneedle introduction, ultrasonic treatment, and iontophoresis. While these methods can promote quick penetration of the drug to the dermis, they cause discomfort to the user (Bok et al., 2023; Dermol-Černe, Pirc & Miklavčič, 2020; Hong et al., 2018). Chemical methods are based on the construction of transfer bodies, microcarriers, and capsules that are easy to penetrate the skin to carry drugs across the skin barrier. While this does not cause discomfort to the user, it often results in changes in the physical and chemical properties of the active ingredient, and certain chemicals have potential known and unknown hazards to the skin (Kalvodová & Zbytovská, 2022; Akram et al., 2022; Damiani & Puglia, 2019). The biological methods include the coupling or fusing of the molecule of interest with screened suitable biomolecule(s) known to have higher transdermal properties (penetrating peptides). This results in the increase of the penetrating potential of the molecule of interest without changing its structure and function (Chablani & Singh, 2022). Transdermal peptides have been widely used in peptide-protein fusion research for pharmacologically significant proteins. Compared to other transdermal delivery strategies, the biological methods have a higher biological safety profile.

Cell-penetrating peptides (CPPs) are effective transdermal delivery systems and powerful transporter tools capable of penetrating the cell membrane and delivering attached biomacromolecules into cells or the cell-microenvironment (Pujals et al., 2006). Cell-penetrating peptides are short peptides with unique cell membrane penetration ability. Currently, hundreds of penetrating peptides have been discovered, of which, several have been used to overcome the skin barrier (Kerkis et al., 2006). Penetrating peptides can be used to mediate the delivery of bimolecular substances such as proteins, peptides, and drug-loaded nanoparticles, and they do not require receptors in vivo and in vitro, and do not cause obvious membrane damage, which also makes penetrating peptides attract great attention in drug research (Nasrollahi et al., 2012). The cytotoxicity of penetrating peptides is also quite low and they will eventually degrade to amino acids; a large number of penetrating peptides with different sequences have been identified to have different transdermal mechanisms and can transport different substances (Reissmann, 2014). The cellular uptake mechanisms of macromolecules delivered by CPP can be divided into direct penetration and endocytic routes, which are affected by many factors such as experimental factors, cell types, and so on (Reissmann (2014) and Sun et al. (2023)). Among these peptides, Translocating peptide 1 (TP1) and Transdermal peptide 1 (TD1) have been heavily investigated and their mechanisms are fairly understood. TD1, a transdermal peptide identified by high-throughput screening, is a peptide chaperone consisting of the ACSSSPHKHCG sequence that facilitates the transdermal delivery of multiple proteins using topical combination delivery. TD1 can help biomacromolecules penetrate the skin through specific binding to the Na, K-ATPase beta subunit (ATP1B1), energy-dependent mechanism, and skin appendages pathway (Ruan et al., 2016). TD1 has been used to enhance the transdermal properties of growth factors such as epidermal growth factor. Ruan et al. fused TD1 with human epidermal growth factor (hEGF) and expressed it in yeast system. Compared with hEGF, the transdermal performance of the fusion protein was significantly improved, and the transdermal mechanism of TD1 was explored at the animal level, thus laying a foundation for the application of TD1 as a transdermal delivery vector (Ruan et al., 2014). Additionally, Jin et al. (2014) fused EGF with double TD1 motifs and showed that both the TD1-hEGF-TD1 and TD1-TD1-hEGF fusion pattern result in further enhancement of the transdermal properties of EGF by 5 times compared to hEGF and 1 time compared to TD1-hEGF. This laid the foundation for the use of TD1 to improve the transdermal ability of proteins and other active substances. The structure and transdermal mechanism of TP1 have been explored by Muñoz-Gacitúa, Guzman & Weiss-López (2022), using nuclear magnetic and isotope labeling methods, and the peptide has been evaluated for its delivery of antitumor drugs. TP1 has been used to deliver active substances such as cabazitaxel in the treatment of prostate cancer and breast cancer (Park et al., 2021). The promising effects of CPPs in transdermal delivery suggest that they are poised to become a preferred bio-transdermal method for hair growth products.

In skincare and haircare research and products, transdermal peptides are used as biological delivery systems and combined with target proteins or peptides forming fusion proteins or peptides. As KGF-2 is a good candidate drug for hair growth, fusing it with transdermal peptide may help in overcoming its low transdermal ability and its thermal instability. This may lead to more clinical applications of KGF-2 even beyond hair growth and skincare.

Plants extracts for hair growth and care

Hair loss, or other problems associated with hair growth, have multifactorial effects on humans as they not only affect appearance but have also been linked to physical and mental health. Presently, drugs such as minoxidil and finasteride are used to prevent hair loss or promote hair growth. However, their effect on hair growth wears off upon withdrawal. The use of these drugs is impeded by the trend of the need for natural products extracted from natural sources such as plants. Plant extracts contain a variety of compounds, such as terpenoids, flavonoids, polyphenolic molecules, carotenoids, and fatty acids, which are known to have positive effects on skin cells (Działo et al., 2016). Unsurprisingly, plant extracts have been used to prevent hair loss and promote hair growth since ancient times. Plant extracts are less likely to be toxic and are easy to obtain at a low cost.

A variety of plant extracts have been confirmed to promote hair growth and prevent hair loss. Although the specific mechanisms of some of these extracts remain elusive, current studies have shown that they are non-toxic, have little to no side effects, and can be acquired and purified easily. To date, nearly a thousand plant extracts have been studied in promoting hair growth, and some show significant effects on hair growth (Choi, Boo & Boo, 2024). Some herbal compounds have been incorporated into hair tonics, hair growth promoters, conditioners, shampoos and other hair products to treat hair loss, dry scalp, and lice infection (Roy, Thakur & Dixit, 2008). These compounds mediate their effects by regulating growth factors in the skin. Roh et al. (2002) showed that Sophora flavescens extract promotes hair growth by inducing and regulating the expression levels of IGF-1 and KGF in dermal cells. Additionally, the extracts also inhibited type II 5α-reductase activity, an effect which was also essential for stimulating hair growth (Roh et al., 2002). Peppermint (Mentha piperita) is another commonly used plant extract in cosmetic and hair products. Investigations by Oh, Park & Kim (2014) demonstrated that 3 percent peppermint oil is a more effective stimulator of hair growth compared to minoxidil of the same concentration. Peppermint oil increases the expression of alkaline phosphatase (ALP) and IGF-1, which in turn induces hair growth (Oh, Park & Kim, 2014). Linololinic acid (LA) extracted from Malva verticillate seeds has also been shown to upregulate KGF, VEGF, HGF, and IGF-1 and promote hair growth in a dose-dependent manner (Ryu et al., 2021). Ryu et al. (2021) showed that LA induces the expression of cell cycle-related proteins such as cyclin D1 and cyclin-dependent kinase 2, and upregulates the Wnt/β-catenin protein signaling pathway, thus, inducing the growth of human follicles dermal papilla cells (HFDPCs) and hair growth. Tectona grandis Linn. seed extracts are used as a hair tonic in Indian traditional medicine and have been demonstrated to induce hair growth similarly to minoxidil (Jaybhaye et al., 2010). Red ginseng has a variety of effects such as antioxidant, anti-tumor, anti-mutagenic, and anti-diabetes; the main active ingredient is ginsenoside. Park et al. (2015) found that red ginseng extract and ginsenoside can enhance the proliferation of human dermal papilla cells (hDPCs), activate ERK and AKT signaling pathways in hDPCs, and up-regulate the proliferation of hair matrix keratinocytes, and also inhibits dihydrotestosterone (DHT) -induced androgen receptor transcription, thereby promoting human hair growth. Extracts from Geranium sibiricum are used to treat diarrhea, bacterial infection, and cancer among other conditions. Boisvert et al. investigated the effects of geranium sibiricum extract on hair growth and found that geranium sibiricum extract significantly reduces the number of mast cells and the expression of transforming growth factor-β(TGF-β) in mouse skin while promoting the expression of HGF and VEGF (Boisvert et al., 2017). By regulating the expression of growth factors and cellular responses, geranium sibiricum extract promotes hair growth (Boisvert et al., 2017). Other plant extracts that have been shown to promote hair growth include extracts from Miscanthus sinensis var. purpurascens (MSP) and Carthamus tinctorius. Jeong et al. (2018) showed that methanol extract from MSP upregulates the expression of HGF and β-catenin in hDPCs and downregulates the expression of TGF-β. Additionally, the extract facilitates hair follicle transition from the resting phase to the growth phase (Jeong et al., 2018). Ethanol extract of Carthamus tinctorius induces dermal and HaCaT cell proliferation and significantly stimulates the expression of hair growth-promoting factors, such as VEGF and KGF. Additionally, the ethanol extract inhibited the expression of TGF-β while significantly increasing the length of cultured hair follicles (Junlatat & Sripanidkulchai, 2014). Extracts from Salvia plebeia, a traditional herbal medicine used to treat hepatitis, menorrhagia, diarrhea, hemorrhoids and other diseases, have also been demonstrated to promote hair growth. Jin et al. (2020) found that the extract of Salvia plebeia can activate proliferation in human dermal cells and promote hair growth by increasing HGF expression and inhibiting TGF-β1 and SMAD2/3 signaling. Shikimic acid (SA), which is present in plant stem cells, has also been demonstrated to promote hair growth and elongation in mouse models by initiating the proliferation of human dermal papilla cells (hDPC) and human outer root sheath cells (hORSC) (Choi et al., 2019). This has led to it being suggested as a potential treatment for alopecia (Choi et al., 2019). In addition to shikimic acid, sinapic acid, caffeine, proanthocyanidins B-3, and ginsenoside Rb1, have all been shown to promote hair growth and elongation (Park & Lee, 2021). Substances such as shikimic acid and sinapic acid contained in plants can regulate hair follicle development and promote hair growth by regulating signaling pathways related to hair follicle development (Choi et al., 2019; Woo et al., 2017). KGF-2 can significantly promote hair follicle development and hair growth. Using plant expression systems to express KGF-2 can explore the synergistic therapeutic effect of plant-derived KGF-2 and active ingredients in plants.

Although the specific mechanism of action of some plant extracts has not been studied, they are non-toxic and have few side effects, are easy to obtain, in line with the current pursuit of pure natural cosmetics and effective products, and have multiple advantages. Taken together, plants already contain multiple active molecules that can promote hair growth, of which some are used in products already on the market. Coupling the expression of recombinant proteins known to promote hair growth in these plants can lead to better hair growth products.

Feasibility of synthesizing TD1-KGF-2 using molecular agriculture

Currently, the expression of recombinant proteins is mainly done in prokaryotic systems or yeast, which has several drawbacks propagated by endotoxin, pathogen contamination, and cost of production. The expression of pharmacologically relevant proteins in plant bioreactors, promises the evasion of these drawbacks while reducing the cost of production. The use of plant bioreactors is also advantageous, as many plant extracts contain useful compounds that promote skin health and hair growth. Fusion protein expression in the plant system can play a synergistic effect of the active components in the plant and foreign proteins, so as to obtain a better therapeutic effect.

A potential model plant for expressing fusion KGF-2 is A. thaliana. Compared with other plant systems, A. thaliana has a clear genetic background and abundant research resources, which is suitable for studying the expression mechanism of foreign proteins. A. thaliana is a model plant with many advantages due to its fast growth rate, short growth cycle, strong adaptability, high genetic transformation efficiency, and large whole-plant biomass (Zheng et al., 2021). A. thaliana extracts are used in cosmetic products, as they contain flavonoid glycoside derivatives, monophenolic compounds, polyphenolic compounds, phenolic acids, and alkaloids among other substances. Additionally, A. thaliana contains substances such as anthocyanins, shikimic acid, and quercitrin, which are known to promote hair growth (Park & Lee, 2021; Mattioli et al., 2019). Thus, A. thaliana is an ideal bioreactor for KGF-2 fusion protein expression, as its content can have synergistic effects with KGF-2, making the extract a better therapeutic. At present, TD1 has a clear transdermal mechanism and related research basis for transdermal efficiency. The fusion expression of TD1 and KGF-2 can enhance the transdermal ability of KGF-2.

In order to ensure the stable expression of TD1 in plants, we will optimize the preference of the TD1 codon and change part of its amino acid residues through point mutation to obtain the TD1 mutant transdermal peptide TDP1. TDP1 is fused to the KGF-2 gene that is also subjected to codon optimization. In the preliminary design, a flexible linker is inserted between the two protein molecules to prevent the structure of the two protein molecules from affecting the function of the fusion protein (Chen, Zaro & Shen, 2013). Selecting appropriate plant expression vectors that contain an enhanced 35S promoter and 35S terminator will increase the accumulation of the fusion protein TDP1-KGF-2. To enhance the transdermal ability of KGF-2 and overcome the difficulties of downstream purification, we selected two fusion protein tags, His-tag and TDP1. Inflorescence transformation can integrate the target gene into the plant genome and stabilize inheritance and whole-plant expression. The A. thaliana inflorescence was infected with Agrobacterium tumeticum and the progeny were screened until the single copy homozygous transgenic A. thaliana was obtained in the third filial generation. Figure 1 is a schematic representation of A. thaliana expressing TDP1-KGF-2. In future studies, the feasibility of TDP1-KGF-2 expression in a whole plant system will be tested in A. thaliana. The expression of fusion protein TDP1-KGF-2 in A. thaliana plant expression system does not cause endotoxin and other problems, and the fusion protein TDP1-KGF-2 can be obtained at a lower cost by optimizing planting conditions and other operations. This enhances the transdermal delivery of KGF-2 while further reducing production costs, thereby increasing its commercial value and applications. The transdermal ability and biological activity of TDP1-KGF-2 will also be evaluated, and hopefully, this will provide a new application model of plant bioreactor in the field of hair growth products for exploring new ideas for the development of natural hair growth raw materials. Plant bioreactors have a broad application prospect in this field.