Dentin-Pulp Complex Regeneration
Vincenzo Guarino, Marco Antonio Alvarez-Pérez in Current Advances in Oral and Craniofacial Tissue Engineering, 2020
Growth factors are proteins that regulate many aspects of cellular function, including survival, morphogenesis, proliferation, migration, apoptosis, differentiation and secretory processes of cells. Growth factors and cytokines are polypeptides or proteins that bind to specific receptors on the surface of target cells; they may act as signaling molecules that modulate cell behavior by mediating intracellular communication. It has been reported that growth factors, as well as bone morphogenic proteins, are essential for tissue engineering in endodontics. Growth factors may be released from the dentin matrix as a result of both injury events to the tissues and clinical restorative procedures. Also, growth factors may be molecules in the signaling of reactionary and reparative dentinogenesis processes (Lind 1996; Smith 2003).
Hormonal Effects on Gastrointestinal Cancer Growth
Jean Morisset, Travis E. Solomon in Growth of the Gastrointestinal Tract: Gastrointestinal Hormones and Growth Factors, 2017
Growth factors and gut hormones may function in an autocrine manner to control growth of gut and pancreatic cancers. Coffey and associates99 found that several different colonic carcinoma cell lines produced both α- and β-transforming growth factor-like substances (TGF-α, TGF-β). Receptors for both EGF and TGF-β were detected in the colon cancer cell lines. Roberts et al.100 reported that TGF-β had no effect on the growth of the HT29 colonic carcinoma cell line, but it inhibited a variety of other noncolonic transformed epithelial cell lines. We find it interesting that none of the colon carcinoma cell lines tested responded to exogenously administered TGF-β or EGF. A human colon cancer cell line has been found to produce both inhibitory (tumor-inhibiting factor) and stimulatory (transforming growth factor) substances.101 Transforming growth factors enhanced the growth of a slow-growing colon cancer cell line but had no effect on growth of the cells that produced it. Increased levels of insulin-like growth factor II messenger RNA (mRNA) were found in rectosigmoid and rectal cancers.102 Thus, growth factors may either stimulate or inhibit cell proliferation. We believe that it is possible that gut hormones may act through modulation of synthesis or release of growth factors which possess different properties.
The Fight Against Cancer
Nathan Keighley in Miraculous Medicines and the Chemistry of Drug Design, 2020
Furthermore, many cancer cells are capable of growing and dividing in the absence of external growth factors because they have the ability to produce their own growth factors; releasing them to stimulates the cells own receptors. Examples of growth factors include platelet-derived growth factor (PDGF) and transforming growth factor-α (TGF-α), which are important in the development of a carcinoma. Cancer cells may also produce abnormal receptors, which are constantly switched on, despite the absence of growth factors. Also, it is possible for a receptor to be over-expressed when an oncogene is too active; coding for excessive quantities of protein receptor in the cell membrane, which means that the cell becomes supersensitive to low levels of growth factor. For example, Ras protein receptors in cancerous cells can be over-abundant and usually lose the ability to auto regulate, being constantly switched on and the signalling pathway for cell division becomes over-active.
A review of the treatment of male pattern hair loss
Published in Expert Opinion on Pharmacotherapy, 2020
Katherine York, Nekma Meah, Bevin Bhoyrul, Rodney Sinclair
Growth factors are signaling molecules secreted by certain cells that stimulate cell proliferation. [65–67] Platelet rich plasma (PRP) is an autologous concentrate of human platelets contained in a small volume of plasma, generated, from centrifugation of patients own venous blood and administered by intradermal injections to the areas of hair loss [66,67]. PRP contains a number of key growth factors secreted by platelets, notably platelet-derived growth factor (PDGF), transforming growth factors (TGF) TGFβ-1 and TGFβ-2, VEGF, basic fibroblastic growth factor, endothelial growth factor and insulin-like growth factors [66–68]. These cytokines are involved in cell proliferation. In this enriched environment, hair growth is stimulated via the upregulation of fibroblastic growth factor β-catenin expression, extracellular signal-regulated kinase (ERK), protein kinase B (PKB) signaling[69]. Interestingly a recent double blind controlled study did not find an association between platelet counts, certain growth factor levels (PDGF, EGF, VEGF) and clinical improvement in response to PRP, indicating other growth factors or mechanisms may be involved in responses seen[70]. PRP also promotes vascularization[71] and prolongs anagen[69]. A recent meta-analysis of 177 patients from six studies reported increased hair density and hair shaft diameter following PRP injections[67]. The main limitation in interpreting PRP efficacy data is the lack of comparability between studies. However, in spite of this PRP is generally considered a safe option in AGA refractory to medical therapy.
Design and fabrication of GelMA/chitosan nanoparticles composite hydrogel for angiogenic growth factor delivery
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Khashayar Modaresifar, Afra Hadjizadeh, Hassan Niknejad
Tissue engineering is founded based on three essential elements: scaffold, cell and signalling factor. Growth factors are an important group of signalling factors which improve tissue formation when having a sustained release and effect on cells. An effective way for delivering growth factors is using nanoparticles. These nanocarriers enable a targeted delivery, long-term impact and overdose prevention [9]. To date, many different nanoparticles have been developed for drug delivery including polymeric nanoparticles, liposomes and niosomes [30]. Chitosan nanoparticles (or nanochitosan), firstly developed by Calvo et al. in 1997, are potent nanocarriers for growth factors due to their biocompatibility and easy method of synthesis [31]. They can be crosslinked by electrostatic interactions between positive functional groups of chitosan and negative functional groups of a polyanion like sodium tripolyphosphate (TPP). The physical crosslinking method preserves the loaded drug or biomolecule [32]. Incorporating nanomaterials and fabricating hybrid hydrogels based on GelMA and other natural or synthetic polymers, give it more specific properties for the final application [12].
Engineered biomaterial strategies for controlling growth factors in tissue engineering
Published in Drug Delivery, 2020
Na Guan, Zhihai Liu, Yonghui Zhao, Qiu Li, Yitao Wang
Growth factors facilitate the proliferation and differentiation of progenitor and stem cells, as well as directly induce growth of differentiated cells such as hepatocytes in the liver or osteoblasts in bone (Uebersax et al., 2009). They also have an important regulatory role in human immunity, hematopoietic regulation, tumorigenesis, inflammatory infection, wound healing, angiogenesis, cell differentiation, cell apoptosis, morphogenesis, and embryo formation (Arisaka & Yui, 2019; Chu et al., 2019; Evans et al., 2019). Growth factors mainly include epidermal growth factor (EGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), and transforming growth factor beta (TGF-β) families (Goh et al., 2016). In the past decades, many researches try to uncover more GFs functions in biomedical science and delivery of GFs using biomaterials has become a pretty hot topic. Currently, numerous researches have shown that scaffolds based on biomaterials could delivery growth factors to promote tissue repair and regeneration at a faster rate (Venkatesan et al., 2017). However, growth factors for clinical applications achieved little clinical success, which were still limited by the instability and safety of GFs (Nicoletti et al., 2019). The key to overcoming the challenges lies in better deliver GFs, maintain their activities and alleviate their adverse effects.