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).
Tissue Engineering of Articular Cartilage
Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi in Articular Cartilage, 2017
The TGF-β superfamily is a class of growth factors that is involved in the repair and inflammation response following injury (Frenkel et al. 2000). Numerous studies have shown that these growth factors can also elicit dramatic changes in articular chondrocytes. TGF-β1 is a popular isoform used in articular cartilage engineering studies. Effects are dependent on parameters such as dose, dosing frequency, and duration, and also the cell type and presence of other stimuli, leading to varied results that range from stimulating chondrogenesis and proliferation (Sporn et al. 1986; Guerne et al. 1994; Blunk et al. 2002) to inhibition of matrix formation (van der Kraan et al. 1992; Verschure et al. 1994) to promoting collagen formation (Sporn et al. 1986; Blunk et al. 2002; Elder and Athanasiou 2009b). The effectiveness of the growth factor is also dependent on the differentiation state of the cells. For example, TGF-β1 stimulated proliferation and proteoglycan synthesis in chondrocytes that were cultured for a week in vitro, but these effects were not apparent on freshly isolated chondrocytes (van der Kraan et al. 1992). Additionally, arthritic chondrocytes experienced a decrease in proteoglycan synthesis when treated with TGF-β1 (Verschure et al. 1994). Chondrocyte phenotype has been shown to change when placed in in vitro culture or in diseased environments, leading to altered responses to not only biochemical but also mechanical stimuli.
Interaction of Immune and Connective Tissue Cells
Brian J. Nickoloff in Dermal Immune System, 2019
The regulation of fibroblast proliferation in vivo involves the complex interaction of a number of factors, including nutrients, oxygen tension,85 temperature,86 cell-cell and cell-matrix contact in three-dimensional planes,87–89 and growth regulatory cytokines. The latter includes such classical growth factors as platelet-derived growth factor (PDGF), epidermal growth factor (EGF), and transforming growth factor-β (TGF-β), whose functions have been recently reviewed.82,83,90–93 In addition, hormones, such as insulin, glucocorticoids, growth hormone, and somatomedins have potent effects on both fibroblast proliferation and matrix synthesis. The focus of this review will be on the role of immune cell-derived cytokines such as interleukins, tumor necrosis factor alpha (TNF-α) and interferons in modulating fibroblast function. The general role of these immune cytokines in growth and repair has been recently reviewed.82,83,93 It should be noted, however, that immune cells are also sources of other growth factors such as TGF-β and PDGF and that nonimmune cells may release “immune” cytokines such as IL-1 and TNF-α.
Drug loaded implantable devices to treat cardiovascular disease
Published in Expert Opinion on Drug Delivery, 2023
Masoud Adhami, Niamh K. Martin, Ciara Maguire, Aaron J. Courtenay, Ryan F. Donnelly, Juan Domínguez-Robles, Eneko Larrañeta
Growth factors, extracellular vesicles, and microRNAs are some examples of bioactive molecules loaded in these acellular cardiac patches. Growth factors are naturally occurring bioactive molecules that affect the growth of cells, for example, stimulating cell proliferation or cellular differentiation [122]. For instance, a combination of both growth factors, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) were loaded in fibrous scaffolds made from poly(l-lactide-co-caprolactone) (PLCL) and poly(2-ethyl-2-oxazoline) (PEOz) by using electrospinning [123]. The results of this study indicated that cells were able to respond at a molecular level by using the growth factors-loaded scaffolds, which also helped to reduce scar tissue formation [123]. In a different work, the authors manufactured a cardiac patch comprising an electronic mesh including multiple electrodes for different purposes, such as cell and tissue electrical stimulation in combination with the sustained release of bioactive molecules within the cardiac tissue [124]. In this study, stromal cell-derived factor-1 (SDF-1) was released from the performed cardiac patch, which was able to stimulate in vitro cell migration. Furthermore, the release of SDF-1 could promote better vascularization [124].
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.
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.