Release Of Platelet-derived Growth Factor Research Articles

Nuclear factor of activated T-cells 5 is indispensable for a balanced adaptive transcriptional response of lung endothelial cells to hypoxia.

Chronic hypoxia causes detrimental structural alterations in the lung, which may cause pulmonary hypertension and are partially mediated by the endothelium. While its relevance for the development of hypoxia-associated lung diseases is well known, determinants controlling the initial adaptation of the lung endothelium to hypoxia remain largely unexplored. We revealed that hypoxia activates the transcription factor nuclear factor of activated T-cells 5 (NFAT5) and studied its regulatory function in murine lung endothelial cells (MLECs). EC-specific knockout of Nfat5 (Nfat5(EC)-/-) in mice exposed to normobaric hypoxia (10% O2) for 21 days promoted vascular fibrosis and aggravated the increase in pulmonary right ventricular systolic pressure as well as right ventricular dysfunction as compared with control mice. Microarray- and single-cell RNA-sequencing-based analyses revealed an impaired growth factor-, energy-, and protein-metabolism-associated gene expression in Nfat5-deficient MLEC after exposure to hypoxia for 7 days. Specifically, loss of NFAT5 boosted the expression and release of platelet-derived growth factor B (Pdgfb)-a hypoxia-inducible factor 1 alpha (HIF1α)-regulated driver of vascular smooth muscle cell (VSMC) growth-in capillary MLEC of hypoxia-exposed Nfat5(EC)-/- mice, which was accompanied by intensified VSMC coverage of distal pulmonary arteries. Collectively, our study shows that early and transient subpopulation-specific responses of MLEC to hypoxia may determine the degree of organ dysfunction in later stages. In this context, NFAT5 acts as a protective transcription factor required to rapidly adjust the endothelial transcriptome to cope with hypoxia. Specifically, NFAT5 restricts HIF1α-mediated Pdgfb expression and consequently limits muscularization and resistance of the pulmonary vasculature.

Near-infrared light-responsive hydrogels for on-demand dual delivery of proangiogenic growth factors

Achieving precise spatiotemporal control over the release of proangiogenic factors is crucial for vasculogenesis, the process of de novo blood vessel formation. Although various strategies have been explored, there is still a need to develop cell-laden biomaterials with finely controlled release of proangiogenic factors at specific locations and time points. We report on the developed of a near-infrared (NIR) light-responsive collagen hydrogel comprised of gold nanorods (GNRs)-conjugated liposomes containing proangiogenic growth factors (GFs). We demonstrated that this system enables on-demand dual delivery of GFs at specific sites and over selected time intervals. Liposomes were strategically formulated to encapsulate either platelet-derived growth factor (PDGF) or vascular endothelial growth factor (VEGF), each conjugated to gold nanorods (GNRs) with distinct geometries and surface plasmon resonances at 710 nm (GNR710) and 1064 nm (GNR1064), respectively. Using near infrared (NIR) irradiation and two-photon (2P) luminescence imaging, we successfully demonstrated the independent release of PDGF from GNR710 conjugated liposomes and VEGF from GNR1064-conjugated liposomes. Our imaging data revealed rapid release kinetics, with localized PDGF released in approximately 4 min and VEGF in just 1 and a half minutes following NIR laser irradiation. Importantly, we demonstrated that the release of each GF could be independently triggered using NIR irradiation with the other GF formulation remaining retained within the liposomes. This light-responsive collagen hydrogels holds promise for various applications in regenerative medicine where the establishment of a guided vascular network is essential for the survival and integration of engineered tissues. Statement of significanceIn this study, we have developed a light-responsive system with gold nanorods (GNRs)-conjugated liposomes in a collagen hydrogel, enabling precise dual delivery of proangiogenic growth factors (GFs) at specific locations and timepoints. Liposomes, containing platelet-derived growth factor (PDGF) or vascular endothelial growth factor (VEGF), release independently under near- infrared irradiation. This approach allows external activation of desired GF release, ensuring high cell viability. Each GF can be triggered independently, retaining the other within the liposomes. Beyond its application in establishing functional vascular networks, this dual delivery system holds promise as a universal platform for delivering various combinations of two or more GFs.

Leukocytes within Autologous Blood Concentrates Have No Impact on the Growth and Proliferation of Human Primary Osteoblasts: An In Vitro Study.

Platelet-rich fibrin (PRF) is a widely used autologous blood concentrate in regenerative medicine. This study aimed to characterize the cellular composition and distribution of different PRF matrices generated by high (710 g) and low (44 g) relative centrifugal forces (RCFs) and to analyze their bioactivity on human primary osteoblasts (pOBs). PRF was separated into upper layer (UL) and buffy coat (BC) fractions, and their cellular contents were assessed using histological and immunohistochemical staining. The release of platelet-derived growth factor (PDGF) and transforming growth factor (TGF-β) was quantified using an ELISA. Indirect PRF treatment on pOBs was performed to evaluate cell viability and morphology. A histological analysis revealed higher quantities of leukocytes and platelets in the low-RCF PRF. TGF-β release was significantly higher in the low-RCF PRF compared to the high-RCF PRF. All PRF fractions promoted pOB proliferation regardless of the centrifugation protocol used. The low-RCF PRF showed higher TGF-β levels than the high-RCF PRF. These findings contribute to understanding the cellular mechanisms of PRF and provide insights into optimizing PRF protocols for bone regeneration, advancing regenerative medicine, and improving patient outcomes.

Harvesting the biochemical potential of L-PRF with their growth factors and cytokines

Leukocyte platelet-rich fibrin (L-PRF) is an autologous biomaterial used in regenerative medicine and tissue healing. This review emphasizes the role of growth factors and cytokines in L-PRF, which contribute significantly to the healing process in various clinical scenarios. The analysis focuses on the controlled release of Platelet-derived growth factors (PDGF), Fibroblast growth factors (FGF), and Vascular endothelial growth factors (VEGF), demonstrating a propensity to promote angiogenesis and stimulate the migration and proliferation of cells necessary for tissue regeneration. The review also examines the roles of anti-inflammatory and pro-inflammatory cytokines, including Interleukins (IL-1, IL-4, IL-10, IL-6) and Tumor necrosis factor-alpha (TNF-α), and Interferon-gamma (IFN-γ), in modulating the inflammatory response during tissue healing. The goal of this comprehensive review is to enhance the understanding of L-PRF and its constituent factors, opening avenues for harnessing its potential in regenerative medicine. The bioactive components within L-PRF stimulate tissue healing and repair, creating an optimal environment for tissue regeneration.

Growth Factors Released from Advanced Platelet-Rich Fibrin in the Presence of Calcium-Based Silicate Materials and Their Impact on the Viability and Migration of Stem Cells of Apical Papilla.

Advanced platelet-rich fibrin (A-PRF) provides the scaffold and growth factors necessary for stem cells to proliferate and differentiate in successful regenerative endodontic procedures. This study investigates the release of transforming growth factor-β1 (TGF-β1), platelet-derived growth factor (PDGF), and vascular endothelial growth factor (VEGF) from A-PRF in cell culture media in the presence and absence of mineral trioxide aggregate (MTA) or Biodentine. Additionally, this research assesses the viability and migration of stem cells of the apical papilla (SCAP) in previously conditioned media. A-PRF obtained from 14 participants were incubated for 7 days in cell culture media alone or via layering with MTA or Biodentine discs and the release of selected growth factors in the media was evaluated using ELISA. The viability of SCAP grown in conditioned media was measured using the CCK8 assay, while SCAP migration was assessed via a transwell assay by counting migrated cells. The release of TGF-β1, PDGF, and VEGF was significantly higher in media with A-PRF alone than in the presence of either calcium-based silicate material (p < 0.05), which showed no difference from the no-A-PRF control (p < 0.05). None of the tested growth factors released in the A-PRF-conditioned media correlated with clot weight. A-PRF-conditioned media, both with and without calcium-based silicate materials, did not impact SCAP viability and migration (p > 0.05). This study shows that SCAP behavior is not impacted by the decrease in growth factor released in the presence of calcium-based silicate materials and that their role in REPs warrants further investigation.

Associations of CSF PDGFRβ With Aging, Blood-Brain Barrier Damage, Neuroinflammation, and Alzheimer Disease Pathologic Changes.

Injured pericytes in the neurovascular unit release platelet-derived growth factor β (PDGFRβ) into the CSF. However, it is not clear how pericyte injury contributes to Alzheimer disease (AD)-related changes and blood-brain barrier (BBB) damage. We aimed to test whether CSF PDGFRβ was associated with different AD-associated and age-associated pathologic changes leading to dementia. PDGFRβ was measured in the CSF of 771 participants with cognitively unimpaired (CU, n = 408), mild cognitive impairment (MCI, n = 175), and dementia (n = 188) from the Swedish BioFINDER-2 cohort. We then checked association with β-amyloid (Aβ)-PET and tau-PET standardized uptake value ratio, APOE ε4 genotype and MRI measurements of cortical thickness, white matter lesions (WMLs), and cerebral blood flow. We also analyzed the role of CSF PDGFRβ in the relationship between aging, BBB dysfunction (measured by CSF/plasma albumin ratio, QAlb), and neuroinflammation (i.e., CSF levels of YKL-40 and glial fibrillary acidic protein [GFAP], preferentially expressed in reactive astrocytes). The cohort had a mean age of 67 years (CU = 62.8, MCI = 69.9, dementia = 70.4), and 50.1% were male (CU = 46.6%, MCI = 53.7%, dementia = 54.3%). Higher CSF PDGFRβ concentrations were related to higher age (b = 19.1, β = 0.5, 95% CI 16-22.2, p < 0.001), increased CSF neuroinflammatory markers of glial activation YKL-40 (b = 3.4, β = 0.5, 95% CI 2.8-3.9, p < 0.001), GFAP (b = 27.4, β = 0.4, 95% CI 20.9-33.9, p < 0.001), and worse BBB integrity measured by QAlb (b = 37.4, β = 0.2, 95% CI 24.9-49.9, p < 0.001). Age was also associated with worse BBB integrity, and this was partly mediated by PDGFRβ and neuroinflammatory markers (16%-33% of total effect). However, PDGFRβ showed no associations with APOE ε4 genotype, PET imaging of Aβ and tau pathology, or MRI measures of brain atrophy and WMLs (p > 0.05). In summary, pericyte damage, reflected by CSF PDGFRβ, may be involved in age-related BBB disruption together with neuroinflammation, but is not related to Alzheimer-related pathologic changes.

The effects of mechanical instability on PDGF mediated inflammatory response at early stage of fracture healing under diabetic condition

Background and ObjectiveMechanical stability plays an important role in fracture healing process. Excessive interfragmentary movement will continuously damage the tissue and newly formed capillaries at the fracture site, which leads to overproduction of platelet-derived growth factor (PDGF) that attracts more macrophages into fracture callus, ultimately persistent and enhanced inflammatory response happens. For diabetic condition, the impact of mechanical instability of fracture site on inflammatory response could be further compliciated and the relevant research in this field is relatively limited. MethodsBuilding on previous experimental studies, this study presents a numerical model consisting of a system of reactive-transport equations representing the transport as well as interactions of different cells and cytokines within the fracture callus. The model is initially validated by available experimental data, and then implemented to investigate the role of mechanical stability of fracture site in inflammatory response during early stage of healing. It is assumed that there is an increased release of PDGF due to the rupture of blood vessels resulting from mechanical instability, which leads to increased production of inflammatory cytokines (i.e., TNF-α). The bone healing process under three different conditions were investigated, i.e., mechanically stable condition with normal inflammatory response (Control, Case 1), mechanically unstable condition with normal inflammatory response (Case 2) and mechanically unstable condition with diabetes (Case 3). ResultsMechanical instability can promote the macrophage infiltration and thus induce an enhanced and prolonged inflammatory response, which could impede the MSCs proliferation during the early fracture healing stage (e.g., compared with the control condition, the MSCs concentration in unstable fracture with normal inflammatory response can be reduced by 3.2% and 5.2% on day 2 and day 10 post-fracture, respectively). Under diabetic condition, the mechanical instability of fracture site could lead to a significant increase of TNF-α concentration in fracture callus (Case 3) in comparison to control (Case 1) (e.g., three-fold increase in TNF-α concentration compared to control). In addition, the results show that the mechanical instability affects the cell differentiation and proliferation in fracture callus in a spatially dependent manner, e.g., for diabetic fracture patients, the mechanical instability could potentially decrease the concentration of MSCs, osteoblasts and chondrocytes by around 39%, 30% and 29% in cortical callus, respectively, in comparison to control. ConclusionThe mechanical instability together with diabetic condition can significantly affect the natural resolution of inflammation during early stage of healing by turning acute inflammation into chronic inflammation which is characterized by a continuously upregulated TNF-α pathway.

Plasma rich in growth factors (PRGF) and leukocyte-platelet rich fibrin (L-PRF): comparative release of growth factors and biological effect on osteoblasts

PurposeTo compare the release of platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF-I) and interleukin 1β (IL-1β) of plasma rich in growth factors (PRGF) and leucocyte platelet-rich fibrin (L-PRF) and to evaluate their biological implication in osteoblasts.MethodsBlood from 3 healthy volunteers was processed into PRGF, immediate L-PRF (L-PRF 0ʹ) and L-PRF 30 min after collection (L-PRF-30ʹ) and a control group. Growth factors release were analyzed at 7 times by ELISA. Cell proliferation, collagen-I synthesis and alkaline phosphatase activity were assessed in primary cultures of human osteoblasts.ResultsA slower controlled release of IGF-I, VEGF and PDGF was observed in the PRGF group at day 14. A higher synthesis of type I collagen was also quantified in PRGF. L-PRF released significantly higher amounts of IL-1β, that was almost absent in the PRGF.ConclusionsThe addition of leukocytes dramatically increases the secretion of proinflammatory cytokines, which are likely to negatively influence the synthesis of type I collagen and alkaline phosphatase (ALP) by osteoblasts.

Genipin modified lyophilized platelet-rich fibrin scaffold for sustained release of growth factors to promote bone regeneration.

Lyophilized platelet-rich fibrin (L-PRF) was shown to further activate resident platelets in platelet-rich fibrin causing a higher amount of growth factors release. However, it still required further experimental studies to resolve the uncontrolled degradation and burst release problem. In this study, the nature crosslinker genipin is introduced to improve the performance of L-PRF scaffold. We used a series of gradient concentration genipin solutions to react with L-PRF. The crosslinking degree, micro morphology, mean pore size, water absorption and mechanical properties of the crosslinked scaffold were evaluated. In order to study the effect of genipin modification on the release kinetics of growth factors from L-PRF, we detected the release of platelet-derived growth factor, vascular endothelial growth factor and transforming growth factor in vitro by ELISA. To investigate the biodegradability of the crosslinked L-PRF in vivo, the scaffolds were transplanted subcutaneously into backs of rats, and the materials were recovered at 1, 2 and 4 weeks after implantation. The biodegradation, inflammatory reaction and biocompatibility of the scaffolds were examined by histological staining. Finally, the genipin crosslinked/uncrosslinked L- Platelet-rich fibrin scaffolds were implanted with freshly prepared SHED cell sheets into rat critical size calvarial defects and the skull samples were recovered to examine the treatment efficacy of genipin crosslinked L-PRF by histologic and radiographic approaches. Results of this study indicated that genipin can be used to modify L-PRF at room temperature at a very low concentration. Genipin-modified L-PRF shows better biomechanical performance, slower biodegradation, good bioavailable and sustained release of growth factors. The 0.01% w/v and 0.1% w/v genipin crosslinked L-PRF have good porous structure and significantly promote cell proliferation and enhance the expression of key genes in osteogenesis in vitro, and work best in promoting bone regeneration in vivo.

Successful healing of non-healing surgical wound based on the release of platelet-derived growth factors from single donor allogeneic platelet-RICH plasma with one freeze-thaw cycle: a case report after a 1-year follow-up

BackgroundNon-healing surgical wounds is a risk in certain patients. Recently, allogenic plasma-rich-platelet (PRP) is used such as regenerative treatment of different non-healing surgical wounds.PurposeWe explore the potential role of using platelet-derived growth factors from single donor PRP, with a freeze-thaw process, for the treatment of surgical scar ulcer.MethodsWe have used a PRP preparation protocol that involved a single cycle of centrifugation at a mean speed of 2400–2800 rpm of donor blood taken with an apheresis machine.ResultsTo our knowledge, this is the first study using the platelet-derived growth factors (PDGF) from single donor apheresis, with a freeze-thaw process. Four weeks after daily application of al-PRP, the ulcer progressed satisfactorily; at six weeks, the ulcer had healed.ConclusionWe concluded that the healing of a surgical wound observed in our case, is promising and suggests that al-PRP might play a role in treating surgical scar ulcers. This must be confirmed in future studies.

Preparation of photothermal-sensitive PDGF@ZIF-8-PDA@COL/PLGA-TCP composite scaffolds for bone defect repair

The repair of bone defects has long been a challenging and significant health question. Here, collagen hydrogel incorporating platelet-derived growth factor (PDGF)-loaded photopolymerizable ZIF-8-PDA nanoparticles (PDGF@ZIF-8-PDA@COL hydrogel) was prepared and perfused into 3D printed poly (lactide-co-glycolide)-tricalcium phosphate (PLGA-TCP) scaffolds. The resulting PDGF@ZIF-8-PDA@COL/PLGA-TCP composite scaffolds were applied as a bone substitute for cranial bone defect repair. The photopolymerizable ZIF-8-PDA nanoparticles had a mean size of 226.2 ± 5.3 nm with photothermal conversion capacity. PDGF@ZIF-8-PDA@COL/PLGA-TCP composite scaffolds showed a slower release of PDGF compared to PDGF release from collagen hydrogels. The composite scaffolds exhibited excellent antibacterial properties and good in vitro osteoconductive capacity. The osteoconductive activities of PDGF@ZIF-8-PDA@COL/PLGA-TCP composite scaffolds were also investigated in a rat cranial bone defect model in vivo by micro-CT imaging, hematoxylin and eosin staining, Masson’s trichrome staining, and immunohistochemical staining of osteogenesis-related markers. The PDGF@ZIF-8-PDA@COL/PLGA-TCP composite scaffolds accelerated cranial bone formation and gradually degraded over time. All these results provided strong evidence that PDGF@ZIF-8-PDA@COL/PLGA-TCP composite scaffolds might be a promising system for bone defect repair.

Biomolecules-releasing click chemistry-based bioadhesives for repairing acetabular labrum tears.

Currently, there are no effective clinical or experimental treatments to fully restore the function of the torn acetabular labrum. To fill the gap, here, we report the finding of progenitor cells in labral tissue, which can be recruited and stimulated to repair torn acetabular labral tissue. This study aimed to develop a biomolecule releasing bioadhesive which can speed up labral tissue healing by eliciting autologous labral progenitor cellular responses. A click chemistry-based bioadhesive, capable of releasing biomolecules, was synthesized to exert ~3× adhesion strength compared with fibrin glue. Via the release of platelet-derived growth factor (PDGF), the adhesive was shown to actively recruit and stimulate the proliferation of labral progenitor cells to the tear sites and within the adhesive. Finally, the ability of this biomolecules-releasing adhesive designed to promote labral tissue regeneration was evaluated using discarded human acetabular labrum tissue compared with surgical suture ex vivo. Histological analysis shows that PDGF-releasing bioadhesive yielded significantly more labrum cell responses and extracellular matrix protein (proteoglycan and collagen) production at the tear tissue site than surgical suture controls. The results confirm that the new PDGF-releasing bioadhesive can activate the responses of autologous labral progenitor cells to significantly improve labral tissue regeneration. Clinical significance: These PDGF-releasing bioadhesives may serve as a new and effective tool for repairing and regenerating acetabular labrum tears.

An Evaluation of the Effect of Activation Methods on the Release of Growth Factors from Platelet-Rich Plasma.

Activation of platelets in platelet-rich plasma may improve growth factor release, thus enhancing regenerative properties. The authors investigated whether different methods of platelet-rich plasma activation affected growth factor release kinetics over time. Platelet-rich plasma from 20 healthy volunteers was processed by six different methods: (1) control (nonactivated); (2) activation with calcium chloride; (3) activation with calcium chloride and ethanol; (4) activation with calcium chloride and ethanol at 4°C; (5) activation with calcium chloride and ethanol with vitamin C; (6) activation with calcium chloride and ethanol with vitamin C at 4°C. Concentration of secreted vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and insulin-like growth factor over 24 hours was measured by immunoassay. Calcium chloride-activated platelet-rich plasma produced significantly more insulin-like growth factor at 1 hour compared to cold and vitamin C platelet-rich plasma, and calcium chloride plus ethanol produced significantly more at 24 hours compared to vitamin C platelet-rich plasma. The addition of vitamin C reduced release of PDGF over time. Activation with calcium chloride and ethanol with or without cold temperature produced a gradual PDGF release as opposed to calcium chloride alone, which caused higher PDGF within 4 hours. There were no significant differences between groups for VEGF, although calcium chloride and cooled platelet-rich plasma approached significance for producing more than vitamin C platelet-rich plasma. Activation of platelet-rich plasma does not significantly improve growth factor secretion, which is made worse by the addition of vitamin C, a platelet inhibitor. Ethanol does not negatively impact growth factor production and may offer a more gradual release. These findings will help guide platelet-rich plasma preparation methods where therapeutic growth factors are used. Therapeutic, V.

Stearoyl-CoA desaturase 1 inhibitor supplemented with gemcitabine treatment reduces the viability and fatty acid content of pancreatic cancer cells in vitro

Abstract Objective: Pancreatic cancer (PC) is an aggressive cancer with ineffective treatment. Inhibition of stearoyl-CoA desaturase 1 (SCD1) suppresses cancer proliferation and might act as a novel chemotherapy supplement, but this has not been investigated in PC. Here, the effects of SCD1 inhibitor CAY10566 supplemented with gemcitabine treatment (gemcitabine+CAY10566) on PC cell viability, apoptosis, phenotype, fatty acid content, platelet-derived growth factor release, and cell size were investigated. Methods: Human PC cell line (PANC-1) was treated with SCD1 inhibitor CAY10566 with or without gemcitabine. Cell viability was assayed using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide and apoptosis and phenotype were determined using flow cytometry. Fatty acid content and platelet-derived growth factor release were measured by enzyme-linked immunosorbent assay. Cell size was determined using scanning electron microscopy. Results: Half-maximal inhibitory concentration of gemcitabine or CAY10566 significantly reduced PANC-1 viability compared to gemcitabine alone (P &lt; .0001). No significant differences in the phenotype of phosphatidylserine, tissue factor or basigin expression were detected at therapeutic doses (P &gt; .05). Apoptosis was significantly increased following incubation with CAY10566 (P &lt; .05). Fatty acid content of cells was significantly higher following gemcitabine treatment compared to CAY10566 alone or gemcitabine+CAY10566 (P &lt; .05). Platelet-derived growth factor released by gemcitabine-treated cells was significantly increased compared to 142 nM CAY10566 alone or gemcitabine+CAY10566 (P &lt; .01). CAY10566 did not affect the size of isolated tumor cells but gemcitabine+CAY10566 significantly increased the size compared to the control (P &lt; .05). Cell viability decreased significantly after the treatment with gemcitabine+CAY10566 compared with CAY10566 alone (P &lt; .05) and gemcitabine alone (P &lt; .01). However, when cycles of chemotherapy were mimicked and treatment was removed, the number of cell viability was significantly reduced (P &lt; .05). Conclusion: This study suggests that CAY10566 may be a suitable supplement for gemcitabine chemotherapy for PC.

Hyaluronic Acid Accelerates VEGF and PDGF Release from Advance Platelet Rich Fibrin in Diabetic Foot Ulcer

BACKGROUND: Hyaluronic acid (HA) is an essential component of extracellular matrix and mediates signaling in wound healing. HA could induce growth factor release from Advanced Platelet Rich Fibrin (A-PRF), including Vascular Endothelial Growth Factor (VEGF) and Platelet-derived Growth Factor (PDGF). However, concentrations of the released-VEGF and PDGF have not been clearly disclosed. Therefore, current study was conducted to measure the release of these growth factors in HA + A-PRF gel of diabetic foot ulcer (DFU) subjects.METHODS: Twenty DFU subjects were included in the study and treated with A-PRF or HA+A-PRF. A-PRF was derived from autologous peripheral blood and processed with low-speed centrifugation. HA was added with a ratio of 1:0.6. A-PRF or HA + A-PRF was applied topically on DFU. Upper tips of A-PRF or HA + A-PRF gels were collected on day 0, 3 and 7 for measurements of VEGF and PDGF concentrations with Enzyme-linked Immune-sorbent Assay (ELISA) methods.RESULTS: On day-3, both VEGF and PDGF concentrations of HA + A-PRF group were significantly higher than the VEGF (p=0.000) and PDGF (p=0.019) concentrations of A-PRF group. The VEGF and PDGF concentrations were continuously and significantly increased on day-7 of HA + A-PRF group, compared to the VEGF (p=0.000) and PDGF (p=0.004) concentrations of A-PRF group.CONCLUSION: Combination HA+A-PRF induces VEGF and PDGF release from A-PRF. A mixture of A-PRF and HA could be more effective than A-PRF alone for treatment of DFU.KEYWORDS: hyaluronic acid, advanced platelet rich fibrin, PRF, growth factor, VEGF, PDGF, diabetic foot ulcer

A bilayer vascular scaffold with spatially controlled release of growth factors to enhance in situ rapid endothelialization and smooth muscle regeneration

When transplanting a scaffold to repair defected vascular tissues, there is a critical need to achieve in-situ rapid endothelialization together with the circumferential alignment and ingrowth of smooth muscle cells. To this end, we hereby design and fabricate a bilayer vascular scaffold with spatially controlled release of growth factors. The lumen of such a scaffold was made of electrospun poly(l-lactide-co-caprolactone) and collagen (PLCL/COL) nanofibers loaded with uniform heparin and vascular endothelial growth factors (VEGF), while its outer layer was composed of circumferentially aligned, PLCL/COL nanofiber yarns loaded with graded platelet derived growth factors (PDGF) increasing from the outermost toward the interior of the scaffold. With the controlled release of VEGF and PDGF from the scaffold, we showed a continuous greater release percentage (ca. 15%) of VEGF relative to PDGF over a duration of almost one month in vitro. At two-month post implantation in a rat abdominal aorta defect model, we observed rapid endothelialization at the luminal surface and orientated smooth muscles infiltrating inside the vascular wall. In particular, loose connective tissues rich in collagen fibers were produced at the outermost layer of the vascular scaffold, indicating the capability of such kind of vascular scaffold for in-situ vascular repair or regeneration.

Interpenetrating Hydrogel Networks Enhance Mechanical Stability, Rheological Properties, Release Behavior and Adhesiveness of Platelet-Rich Plasma.

Platelet-rich plasma (PRP) has attracted much attention for the treatment of articular cartilage defects or wounds due to its intrinsic content of growth factors relevant for tissue repair. However, the short residence time of PRP in vivo, due to the action of lytic enzymes, its weak mechanical properties and the consequent short-term release of bioactive factors has restricted its application and efficacy. The present work aimed at designing new formulation strategies for PRP, based on the use of platelet concentrate (PC)-loaded hydrogels or interpenetrating polymer networks, directed at improving mechanical stability and sustaining the release of bioactive growth factors over a prolonged time-span. The interpenetrating hydrogels comprised two polymer networks interlaced on a molecular scale: (a) a first covalent network of thermosensitive and biodegradable vinyl sulfone bearing p(hydroxypropyl methacrylamide-lacate)-polyethylene glycol triblock copolymers, tandem cross-linked by thermal gelation and Michael addition when combined with thiolated hyaluronic acid, and (b) a second network composed of cross-linked fibrin. The PC-loaded hydrogels, instead, was formed only by network (a). All the designed and successfully synthesized formulations greatly increased the stability of PRP in vitro, leading to significant increase in degradation time and storage modulus of PRP gel. The resulting viscoelastic networks showed the ability to controllably release platelet derived growth factor and transforming growth factr β1, and to improve the tissue adhesiveness of PRP. The newly developed hydrogels show great potential for application in the field of wound healing, cartilage repair and beyond.

The evaluation of leukocyte-platelet rich fibrin as an anti-inflammatory autologous biological additive. A novel in vitro study.

Objectives:To investigate the use of leukocyte-platelet rich fibrin on suppressing the porphyromonas gingivalis (PG-LPS)-induced secretion of proinflammatory cytokines.Methods:This quantitative experimental study was conducted at the School and Hospital of Stomatology, Jilin University, Changchun, China, between September 2017 and January 2019. A modified technique was used to obtain human gingival fibroblast cells (HGFCs). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Cell Counting Kit-8 tests were established to determine the proliferation rate. Human gingival fibroblast cells were treated by PG-LPS at different periods and the isolated mRNA was subjected to reverse transcription polymerase chain reaction and real time quantitative polymerase chain reaction. The release of platelet-derived growth factor and transforming-growth factor-β1 at various time intervals was observed.Results:We successfully established a modified technique for the production of HGFCs culture. One µg/mL PG-LPS was the recommended concentration to inhibit fibroblast proliferation. The expression of the pro-inflammatory cytokines messenger ribnucleic acid was notably raised at 3 and 6 hours post-PG-LPS treatment. The cumulative release of growth factors peaked during the first 24 hours and the production continued for 10 days. However, the fibroblast expression of cytokines was significantly suppressed after treatment with leucocyte- and platelet-rich fibrin (L-PRF).Conclusion:This study provided a novel way of obtaining HGFCs and greater understanding of the clinical impacts through the assessment of the anti-inflammatory properties of L-PRF in vitro.

Application of pulsed electric fields for the valorization of platelets with no therapeutic value for transfusion medicine

Platelets are blood components with high biomedical potential due to their physiological role in wound healing and their rich growth factor content. This paper describes proof-of-concept experiments aimed to produce a new blood-derived product by applying pulsed electric fields (PEF) to platelet concentrates (PC) with no therapeutic value for transfusion medicine. A human platelet concentrate suspension was subjected to a PEF treatment of 1 pulse, 5[Formula: see text]kV/cm, for 2[Formula: see text][Formula: see text]s. Release of platelet-derived growth factor (PDGF) from the electroporated platelets was measured by ELISA. Furthermore, the biological activity of the obtained blood-derived product was characterized. Human mesenchymal stem cells (hMSC) were cultured in the presence of the proteins released from the platelets after PEF application and evaluated for their expansion potential. Results show that platelet concentrates subjected to a single PEF treatment can release PDGF to the supernatant. Protein release from the single and transient PEF cycle was confirmed by the expansion of hMSC cultured with a medium supplemented with the platelet releasate obtained from electroporated platelets. These results demonstrate the potential of a new application of PEF for the valorization of PC into a biomedical product with therapeutic value.

Injectable Macroporous Hydrogel Formed by Enzymatic Cross-Linking of Gelatin Microgels.

Injectable hydrogels can be useful tools for facilitating wound healing since they conform to the irregular shapes of wounds, serving as a temporary matrix during the healing process. However, the lack of inherent pore structures of most injectable hydrogels prohibits desired interactions with the cells of the surrounding tissues limiting their clinical efficacy. Here, we introduce a simple, cost-effective and highly biofunctional injectable macroporous hydrogel made of gelatin microgels crosslinked by microbial transglutaminase (mTG). Pores are created by the interstitial space among the microgels. A water-in-oil emulsion technique was used to create gelatin microgels of an average size of 250μm in diameter. When crosslinked with mTG, the microgels adhered to each other to form a bulk hydrogel with inherent pores large enough for cell migration. The viscoelastic properties of the porous hydrogel were similar to those of nonporous gelatin hydrogel made by adding mTG to a homogeneous gelatin solution. The porous hydrogel supported higher cellular proliferation of human dermal fibroblasts (hDFs) than the nonporous hydrogel over two weeks, and allowed the migration of hDFs into the pores. Conversely, the hDFs were unable to permeate the surface of the nonporous hydrogel. To demonstrate its potential use in wound healing, the gelatin microgels were injected with mTG into a cut out section of an excised porcine cornea. Due to the action of mTG, the porous hydrogel stably adhered to the cornea tissue for two weeks. Confocal images showed that a large number of cells from the cornea tissue migrated into the interstitial space of the porous hydrogel. The porous hydrogel was also used for the controlled release of platelet-derived growth factor (PDGF), increasing the proliferation of hDFs compared to the nonporous hydrogel. This gelatin microgel-based porous hydrogel will be a useful tool for wound healing and tissue engineering.