Initial Healing Phase Research Articles

In Vitro Wound-Healing Potential of Phenolic and Polysaccharide Extracts of Aloe vera Gel.

The present study aimed to conduct a comparative investigation of the biological properties of phenolic and polysaccharide extracts obtained using an ultrasound-assisted technique from Aloe vera gel and their effects on each stage of the wound healing process in in vitro experimental models. HPLC analysis showed that the phenolic extract contained aloin, ferulic, and caffeic acid, as well as quercetin dihydrate, as major compounds. Capillary zone electrophoresis indicated the prevalence of mannose and glucose in the polysaccharide extract. Cell culture testing revealed the anti-inflammatory properties of the phenolic extract at a concentration of 0.25 mg/mL through significant inhibition of pro-inflammatory cytokines-up to 28% TNF-α and 11% IL-8 secretion-in inflamed THP-1-derived macrophages, while a pro-inflammatory effect was observed at 0.5 mg/mL. The phenolic extract induced 18% stimulation of L929 fibroblast proliferation at a concentration of 0.5 mg/mL, enhanced the cell migration rate by 20%, and increased collagen type I synthesis by 18%. Moreover, the phenolic extract exhibited superior antioxidant properties by scavenging free DPPH (IC50 of 2.50 mg/mL) and ABTS (16.47 mM TE/g) radicals, and 46% inhibition of intracellular reactive oxygen species (ROS) production was achieved. The polysaccharide extract demonstrated a greater increase in collagen synthesis up to 25%, as well as antibacterial activity against Staphylococcus aureus with a bacteriostatic effect at 25 mg/mL and a bactericidal one at 50 mg/mL. All these findings indicate that the phenolic extract might be more beneficial in formulations intended for the initial phases of wound healing, such as inflammation and proliferation, while the polysaccharide extract could be more suitable for use during the remodeling stage. Moreover, they might be combined with other biomaterials, acting as efficient dressings with anti-inflammatory, antioxidant, and antibacterial properties for rapid recovery of chronic wounds.

The Impact of Low-Power Therapeutic Lasers at 904 nm on the Healing Process of Wounds and the Relationships Between Extracellular Matrix Components and Myofibroblasts.

The goal of the study was to further our understanding of the functions that myofibroblasts do, how they interact with the matrix's extracellular elements, and how laser therapy at 904 nm works. Thirty Wistar rats with superficial wounds on the backs were used in this study. The laser therapy device used two energy levels of a 904 nm laser with an output power of 60 mW. The outcomes had been evaluated for one, three, five, seven, and fourteen days following laser therapy. Numerous methods, including as histology, immunohistochemistry, and scanning electron microscopy, have been used to evaluate the tissues.There was a statistically important (P ≤ .05) decrease in the number of inflammatory cells and the degree of edema after laser therapy. On the other hand, the amounts of elastic fiber as well as collagen slightly increased. On the third post-laser treatment day, there was a statistically significant distinction (P < .05) in the number of myofibroblasts with the desmin; smooth muscle alpha-actin phenotype between the laser-treated and control groups.These results suggest that, compared to a higher energy of 5.6 J, laser therapy at a lower energy of 3.6 J may be more effective in stimulating myofibroblast differentiation during the initial phases of wound healing. These findings show how low-power laser therapy promotes wound healing.

Hypoxic-Normoxic Crosstalk Activates Pro-Inflammatory Signaling in Human Cardiac Fibroblasts and Myocytes in a Post-Infarct Myocardium on a Chip.

Myocardial infarctions locally deprive myocardium of oxygenated blood and cause immediate cardiac myocyte necrosis. Irreparable myocardium is then replaced with a scar through a dynamic repair process that is an interplay between hypoxic cells of the infarct zone and normoxic cells of adjacent healthy myocardium. In many cases, unresolved inflammation or fibrosis occurs for reasons that are incompletely understood, increasing the risk of heart failure. Crosstalk between hypoxic and normoxic cardiac cells is hypothesized to regulate mechanisms of repair after a myocardial infarction. To test this hypothesis, microfluidic devices are fabricated on 3D printed templates for co-culturing hypoxic and normoxic cardiac cells. This system demonstrates that hypoxia drives human cardiac fibroblasts toward glycolysis and a pro-fibrotic phenotype, similar to the anti-inflammatory phase of wound healing. Co-culture with normoxic fibroblasts uniquely upregulates pro-inflammatory signaling in hypoxic fibroblasts, including increased secretion of tumor necrosis factor alpha (TNF-α). In co-culture with hypoxic fibroblasts, normoxic human induced pluripotent stem cell (hiPSC)-derived cardiac myocytes also increase pro-inflammatory signaling, including upregulation of interleukin 6 (IL-6) family signaling pathway and increased expression of IL-6 receptor. Together, these data suggest that crosstalk between hypoxic fibroblasts and normoxic cardiac cells uniquely activates phenotypes that resemble the initial pro-inflammatory phase of post-infarct wound healing.

TGF-Β Isoforms: TGF-β1, TGF-β2 and TGF-β3 in Ligament and Tendon Healing

Abstract Introduction. Tendon and ligament injuries affect people of all ages, including professional athletes. Tumor Growth Factor β (TGF- β) isoforms play a significant role in the regeneration of tendons and ligaments, such as through the recruitment of macrophages and fibroblasts or the regulation of the formation of extracellular matrix (ECM). Although the TGF- β family regulates signalling pathways related to the healing process, excessive TGF- β activation can lead to fibrosis and the formation of scars and adhesions. This article recapped the significance of TGF- β isoforms TGF- β1, TGF- β2, and TGF- β3 in the physiological healing of injured tendons and ligaments. Material and Methods. A total of 1434 articles were identified using the PubMed search string (TGF-β isoforms or TGF-β1 or tgfb1 or TGF-β2 or tgfb2 or TGF-β3 or tgfb3) and (tendon or ligament). Human studies, animal models and in vitro cultures were included in the search. Forty-nine published articles were included. Results. Histologic evidence demonstrated greater ligament and tendon regeneration and collagen type I expression when using TGF-β1, often leading to fibrosis. TGF-β3 inhibits the TGF-β1 and TGF-β2 by switching Smad2/3 signaling to Smad7 and CREB-1 transcription factor. There was a delay in TGF-β3 level peak compared to other isoforms. Conclusions. All 3 TGF-β isoforms seem to play a significant role in the subsequent stages of healing. We state a hypothesis that during the initial phase of tendon and ligament healing, TGF-β1 levels need to be elevated. Further, TGF-β3 may inhibit the action of TGF-β1 and TGF-β2, which leads to the inhibition of inflammation and changes in ECM production, and consequently to a reduction in the level of scarring.

Porous Precision-Templated 40 μm Pore Scaffolds Promote Healing through Synergy in Macrophage Receptor with Collagenous Structure and Toll-Like Receptor Signaling.

Porous precision-templated scaffolds (PTS) with uniform, interconnected, 40 μm pores have shown favorable healing outcomes and a reduced foreign body reaction (FBR). Macrophage receptor with collagenous structure (MARCO) and toll-like receptors (TLRs) have been identified as key surface receptors in the initial inflammatory phase of wound healing. However, the role of MARCO and TLRs in modulating monocyte and macrophage phenotypes within PTS remains uncharacterized. In this study, we demonstrate a synergetic relationship between MARCO and TLR signaling in cells inhabiting PTS, where induction with TLR3 or TLR4 agonists to 40 μm scaffold-resident cells upregulates the transcription of MARCO. Upon deletion of MARCO, the prohealing phenotype within 40 μm PTS polarizes to a proinflammatory and profibrotic phenotype. Analysis of downstream TLR signaling shows that MARCO is required to attenuate nuclear factor kappa B (NF-κB) inflammation in 40 μm PTS by regulating the transcription of inhibitory NFKB inhibitor alpha (NFKBIA) and interleukin-1 receptor-associated kinase 3 (IRAK-M), primarily through a MyD88-dependent signaling pathway. Investigation of implant outcome in the absence of MARCO demonstrates an increase in collagen deposition within the scaffold and the development of tissue fibrosis. Overall, these results further our understanding of the molecular mechanisms underlying MARCO and TLR signaling within PTS. Impact statement Monocyte and macrophage phenotypes in the foreign body reaction (FBR) are essential for the development of a proinflammatory, prohealing, or profibrotic response to implanted biomaterials. Identification of key surface receptors and signaling mechanisms that give rise to these phenotypes remain to be elucidated. In this study, we report a synergistic relationship between macrophage receptor with collagenous structure (MARCO) and toll-like receptor (TLR) signaling in scaffold-resident cells inhabiting porous precision-templated 40 μm pore scaffolds through a MyD88-dependent pathway that promotes healing. These findings advance our understanding of the FBR and provide further evidence that suggests MARCO, TLRs, and fibrosis may be interconnected.

UNDERSTANDING THE BIOMECHANICAL RESPONSE OF PROGRESSIVE THREAD DENTAL IMPLANTS USING MULTI-SCALE FINITE ELEMENT ANALYSIS

Implant osseointegration is an important factor dictating its long-term efficacy in situ. Along with various biological factors, it is greatly influenced by the mechanical stimulus at the peri-implant bone. The present study aims to understand the biomechanical response of progressive thread dental implants using multi-scale-based finite element analysis employing macro and micro models of bone. &amp;mu;-CT images of a cadaveric human mandible of its premolar region were obtained, along with CT scan of the same region to generate computational models. Total of six dental implants were designed having regular and progressive thread depths. Three different stages of healing of the bone-implant assembly were simulated parametrically. The biomechanical environment at the peri-implant bone was analyzed considering the 'Mechanostat' hypothesis. The obtained results revealed that bone strain is significantly higher during the initial healing phase when the bone is weakest. During this phase, implant stress and its displacement in both buccolingual and coronoapical directions are also noticeably higher. Also, displacements of progressive thread implants were lower in all the healing phases as compared to the implants with constant thread depth. The observations of this &amp;mu; FEA study highlights the clinical applicability of a progressive thread dental implant as it generates larger functional surface area, thus engages higher trabeculae and therefore is suitable for weaker bone conditions. Furthermore, by comparing the stress values at bone and implant between the two bone models, the CT-based model having inhomogeneous material was deemed suitable as an alternative to computationally expensive &amp;mu; FEA.

Alleviating hypoxia and oxidative stress for treatment of cardiovascular diseases: a biomaterials perspective.

A state of hypoxia (lack of oxygen) persists in the initial and later phases of healing in cardiovascular diseases, which can alter the tissue's repair or regeneration, ultimately affecting the structure and functionality of the related organ. Consequently, this results in a cascade of events, leading to metabolic stress and the production of reactive oxygen species (ROS) and autophagy. This unwanted situation not only limits the oxygen supply to the needy tissues but also creates an inflammatory state, limiting the exchange of nutrients and other supplements. Consequently, biomaterials have gained considerable attention to alleviate hypoxia and oxidative stress in cardiovascular diseases. Numerous oxygen releasing and antioxidant biomaterials have been developed and proven to alleviate hypoxia and oxidative stress. This review article summarizes the mechanisms involved in cardiovascular pathologies due to hypoxia and oxidative stress, as well as the treatment modalities currently in practice. The applications, benefits and possible shortcomings of these approaches have been discussed. Additionally, the review explores the role of novel biomaterials in combating the limitations of existing approaches, primarily focusing on the development of oxygen-releasing and antioxidant biomaterials for cardiac repair and regeneration. It also directs attention to various other potential applications with critical insights for further advancement in this area.

Use Of Apitherapy: A Sweet Approach To Bony Healing Of Extracted Tooth Socket

Objective: To determine the effect of honey in enhancing the height of bony socket healing after tooth extraction. Methods: This Quasi-experimental study includes 100 patients had were selected through convenience sampling and divided into two groups, i.e. 50 each. A tooth radiograph was taken both preoperatively and postoperatively followed by nonsurgical extraction of tooth. The experimental group was provided with honey and instructed to apply it 3 times daily for the next 10 days using an I/V syringe so that honey reached up to the depth of the socket during the initial healing phase. On the 90th postoperative day, patients were repeated with the periapical radiograph. The bony outline of the extracted tooth socket was traced on a tracing paper on the preoperative radiograph and the 90th postoperative day of the radiograph and compared for wound healing by overlapping and measuring the height through a ruler. Hence, the post-operative height of the socket was evaluated in both groups. Data were analyzed using SPSS version 17.0. Results: The mean age was 30.76 ± 6.57 and 31.02 ± 5.97 years in the non-honey and honey group respectively. A total of 24 (48%) subjects were male in the honey group compared with the non-honey group 19 (38%). Females were 26 (52%) and 31 (62%) in the honey group and non-honey group. Statistically significant (p-value 0.001) was observed between the radiological Height of the socket on 90 days in honey and non-honey groups. Conclusion: It has been determined that honey is significantly efficient honey in enhancing the height of bony socket healing after tooth extraction. To encourage adequate socket repair after tooth extraction, it may be given as a postoperative treatment.

Preparation of Enzyme-Soluble Swim Bladder Collagen from Sea Eel (Muraenesox cinereus) and Evaluation Its Wound Healing Capacity.

In the present research, the enzyme-facilitated collagen from sea eel (Muraenesox cinereus) swim bladder was isolated, and the collagen characteristics were analyzed. Then, the collagen sponge was prepared and its potential mechanism in promoting skin wound healing in mice was further investigated. Collagen was obtained from the swim bladder of sea eels employing the pepsin extraction technique. Single-factor experiments served as the basis for the response surface method (RSM) to optimize pepsin concentration, solid-liquid ratio, and hydrolysis period. With a pepsin concentration of 2067 U/g, a solid-liquid ratio of 1:83 g/mL, and a hydrolysis period of 10 h, collagen extraction achieved a yield of 93.76%. The physicochemical analysis revealed that the extracted collagen belonged to type I collagen, and the collagen sponge displayed a fibrous structure under electron microscopy. Furthermore, in comparison to the control group, mice treated with collagen sponge dressing exhibited elevated activities of superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (T-AOC), and glutathione peroxidase (GSH-Px), and decreased levels of malondialdehyde (MDA), interleukin (IL)-1β, interleukin (IL)-6, and tumor necrosis factor (TNF)-α. The collagen sponge dressing effectively alleviated inflammation in the wound area, facilitating efficient repair and rapid healing of the skin tissue. During the initial phase of wound healing, the group treated with collagen sponge dressing exhibited an enhancement in the expressions of cluster of differentiation (CD)31, epidermal growth factor (EGF), transforming growth factor (TGF)-β1, and type I collagen, leading to an accelerated rate of wound healing. In addition, this collagen sponge dressing could also downregulate the expressions of CD31, EGF, and type I collagen to prevent scar formation in the later stage. Moreover, this collagen treatment minimized oxidative damage and inflammation during skin wound healing and facilitated blood vessel formation in the wound. Consequently, it exhibits significant potential as an ideal material for the development of a skin wound dressing.

Autologous blood clots: a natural biomaterial for wound healing

Repair after injury in mammalian tissue involves a complex cascade of events, with the formation of local blood clots being essential for the initial phases of wound healing. As a result, emerging research has sought to harness this biological activity to generate a pro-regenerative biomaterial to speed up wound healing. According to recent studies, “blood clots” created in vitro can be employed as an orthobiologic-based biomaterial for promoting tissue regeneration. Even though such research is still in its early phases, numerous studies show encouraging results that suggest autologous blood clots created in vitro might be a valuable treatment for soft tissue and orthopedic injuries. In this article, we discuss the function of blood clots in physiologic healing, how exogenous material can affect this process, and the most recent clinical research that proposes the use of autologous blood clots as a therapeutically beneficial biomaterial.

The effect of Salvadora persica ethanolic extract on oral tissue healing in rats: An in vivo study

IntroductionInvasive surgical procedures in the oral cavity inevitably cause trauma to the soft and hard tissues. The healing process in the oral cavity tissue occurs in a complex manner involving different types of cells, maturation process, and the time of healing. Salvadora persica (miswak) has been found to exert various positive effects on the oral cavity, including antimicrobial, anti-gingivitis, anti-cariogenic, gingival healing, and teeth whitening properties. This study aims to investigate the potential of miswak as an adjunctive therapy in promoting wound healing. Materials and methods30 live Sprague-Dawley rats were used in this study. The rats’ mandibular first molar tooth was extracted, and an incision wound was made on the tongue. The extraction socket and incision wound were irrigated using normal saline and different concentrations of locally processed miswak plant extracts (0.05%, 10%, and 20%) for 7 days. The rats were sacrificed for gross examination of the tooth socket and tongue healing. Both soft tissue and alveolar bone were examined microscopically. ResultsComplete closure of the incision wound was observed on all rats’ tongues; miswak groups showed better wound healing than control and placebo groups in the oral mucosa overlying the alveolar bones. 0.05% and 20% miswak extracts showed prominent wound healing effects in the sagittal sections of the tongue, with moderate formation of connective tissue under the wound site and notable wound contraction. The 20% miswak extract group showed the highest percentage of healed oral mucosa on the alveolar bone and higher bone deposition at the alveolar base. ConclusionA concentration of 20% miswak extract enhances the initial phase of wound healing both in oral soft and hard tissues. Miswak extract at this concentration was not toxic to the tissues and had potential therapeutic effects in oral tissue healing.

Citral Modulates MMP-2 and MMP-9 Activities on Healing of Gastric Ulcers Associated with High-Fat Diet-Induced Obesity.

Obesity causes low-grade inflammation that results in the development of comorbidities. In people with obesity, exacerbation of gastric lesion severity and delayed healing may aggravate gastric mucosal lesions. Accordingly, we aimed to evaluate the citral effects on gastric lesion healing in eutrophic and obese animals. C57Bl/6 male mice were divided into two groups: animals fed a standard diet (SD) or high-fat diet (HFD) for 12 weeks. Gastric ulcers were induced using acetic acid (80%) in both groups. Citral (25, 100, or 300 mg/kg) was administered orally for 3 or 10 days. A vehicle-treated negative control (1% Tween 80, 10 mL/kg) and lansoprazole-treated (30 mg/kg) were also established. Lesions were macroscopically examined by quantifying regenerated tissue and ulcer areas. Matrix metalloproteinases (MMP-2 and -9) were analyzed by zymography. The ulcer base area between the two examined periods was significantly reduced in HFD 100 and 300 mg/kg citral-treated animals. In the 100 mg/kg citral-treated group, healing progression was accompanied by reduced MMP-9 activity. Accordingly, HFD could alter MMP-9 activity, delaying the initial healing phase. Although macroscopic changes were undetectable, 10-day treatment with 100 mg/kg citral exhibited improved scar tissue progression in obese animals, with reduced MMP-9 activity and modulation of MMP-2 activation.

Landscape of Well-Coordinated Fracture Healing in a Mouse Model Using Molecular and Cellular Analysis.

The success of fracture healing relies on overlapping but coordinated cellular and molecular events. Characterizing an outline of differential gene regulation throughout successful healing is essential for identifying crucial phase-specific markers and may serve as the basis for engineering these in challenging healing situations. This study analyzed the healing progression of a standard closed femoral fracture model in C57BL/6N (age = 8 weeks) wild-type male mice. The fracture callus was assessed across various days post fracture (D = days 0, 3, 7, 10, 14, 21, and 28) by microarray, with D0 serving as a control. Histological analyses were carried out on samples from D7 until D28 to support the molecular findings. Microarray analysis revealed a differential regulation of immune response, angiogenesis, ossification, extracellular matrix regulation, mitochondrial and ribosomal genes during healing. In-depth analysis showed differential regulation of mitochondrial and ribosomal genes during the initial phase of healing. Furthermore, the differential gene expression showed an essential role of Serpin Family F Member 1 over the well-known Vascular Endothelial Growth Factor in angiogenesis, especially during the inflammatory phase. The significant upregulation of matrix metalloproteinase 13 and bone sialoprotein from D3 until D21 asserts their importance in bone mineralization. The study also shows type I collagen around osteocytes located in the ossified region at the periosteal surface during the first week of healing. Histological analysis of matrix extracellular phosphoglycoprotein and extracellular signal-regulated kinase stressed their roles in bone homeostasis and the physiological bone-healing process. This study reveals previously unknown and novel candidates, that could serve as a target for specific time points in healing and to remedy cases of impaired healing.

Three-Dimensional Computational Model Simulating the Initial Callus Growth during Fracture Healing in Long Bones: Application to Different Fracture Types.

Bone fractures are among the most common and potentially serious injuries to the skeleton, femoral shaft fractures being especially severe. Thanks to recent advances in the area of in silico analysis, several approximations of the bone healing process have been achieved. In this context, the objective of this work was to simulate the initial phase of callus formation in long bones, without a pre-meshed domain in the 3D space. A finite element approach was computationally implemented to obtain the values of the cell concentrations along the whole domain and evaluate the areas where the biological quantities reached the thresholds necessary to trigger callus growth. A voxel model was used to obtain the 3D domain of the bone fragments and callus. A mesh growth algorithm controlled the addition of new elements to the domain at each step of the iterative procedure until complete callus formation. The implemented approach is able to reproduce the generation of the primary callus, which corresponds to the initial phase of fracture healing, independently of the fracture type and complexity, even in the case of several bone fragments. The proposed approach can be applied to the most complex bone fractures such as oblique, severely comminuted or spiral-type fractures, whose simulation remains hardly possible by means of the different existing approaches available to date.

Facial implant gingival level and thickness changes following maxillary anterior immediate tooth replacement with scarf-connective tissue graft: A 4-13-year retrospective study.

A scarf-shaped connective tissue graft can be placed at the facial and proximal aspect of the peri-implant soft tissue zone during immediate implant placement and provisionalization (IIPP) procedures in the esthetic zone to optimize implant esthetics without the need of flap reflection. This retrospective study evaluated soft tissue stability after scarf-connective tissue graft (S-CTG) in conjunction with IIPP procedures in the esthetic zone. Patients who received IIPP with S-CTG with a minimum 1-year follow-up were evaluated. Mid-facial gingival level (MFGL) change and mid-facial gingival thickness (MFGT) change were measured and compared at the pre-op (T0), IIPP + S-CTG surgery (T1), follow up appointment with MFGT measurement (T2), and latest follow-up appointment (T3). Implant success rate and graft necrosis were also recorded. A total of 22 IIPP and S-CTG procedures in 20 patients were evaluated in the study. After a mean follow-up of 8.2 years (3.9-13.4) (T3), all implants remained osseointegrated (22/22 [100%]), with statistically insignificant mean midfacial gingival level change of -0.19 mm (-1.5 to 0.8). Statistically significant difference in midfacial gingival thickness (MFGT) was noted (2.5 mm [1.8-3.5 mm]) after a mean follow-up time (T2) of 2.3 years (1-8.6) when compared with MFGT at baseline (1.1 mm [0.6-1.3 mm]) (T1). Necrosis of S-CTG during initial healing phase was noted in 9% (2/22) of the sites. Within the confines of this study, scarf-connective tissue graft at time of immediate implant placement and provisionalization can thicken the gingiva and maintain the gingival level at the critical soft tissue zone. Managing the soft tissue zone is as important as that of the hard tissue zone for peri-implant esthetics. Connective tissue graft is one of the methods that can enhance the final esthetic outcomes. This retrospective study has demonstrated that Scarf-CTG technique is an effective treatment modality to maintain soft tissue stability.

Pilonidal disease: A new look at an old disease

Pilonidal disease is a very common affliction that affects mainly young, hirsute, obese males during their young adult years of life. Previous etiological theories of this ailment centred on congenital causes. The current understanding is that pilonidal disease is an acquired affliction. Some patients, however, may have confounding hereditary tendencies to form pilonidal disease. There is a myriad of methods of treatment for chronic pilonidal disease. Such treatments vary from the creation of large skin flaps to simple instillation of chemicals into the sinuses. No single technique is favoured by every surgeon and each technique has its ardent supporters. The current favoured treatments however, are toward the use of the less invasive options compared to the large extensive flaps. Favoured options include minimally invasive techniques as well as simple lay open and marsupialisation. No proposed classification system for the assessment of severity of pilonidal disease has correlated disease severity with treatment options. Therefore, no classification system is in widespread use by the surgical community. Post-operative supportive management, especially in the early post-operative period, and laser hair epilation after the initial healing phase, have some usefulness in the overall treatment of pilonidal disease.

A Comprehensive Review on Efficacy of Leukocyte and Platelet-rich Fibrin (L-PRF) Administration in Reconstruction of Oral and Maxillofacial Structures

Several studies have shown that growth factors are effective in soothing inflammatory processes involved in the initial hemostasis phase of wound healing. Leukocyte and platelet-rich fibrin (L-PRF) is the second generation of concentrated platelets that have been shown to stimulate the proliferation of osteoblasts, gingival fibroblasts, and periodontal ligament cells. Rich platelet components have an immune function and antibacterial properties, which play a critical role in the wound healing process. The present study aimed to review the reported documents on L-PRF administration in regeneration and wound healing of oral and maxillofacial surgeries. The research was performed using well-known medical databases to find controlled clinical trials that used L-PRF as a cotreatment strategy during oral and maxillofacial surgeries. Eligible articles published between 2000 and 2022 in PubMed, Web of Science, Science Direct, and Scopus databases were selected for this review. According to the results of this study, L-PRF has significant effectiveness as a maxillofacial regenerative therapy by improving para-clinical parameters after surgery. However, more clinical practice and additional research are essential for the development of this complementary treatment method

MIF does only marginally enhance the pro-regenerative capacities of DFO in a mouse-osteotomy-model of compromised bone healing conditions.

The initial phase of fracture healing is crucial for the success of bone regeneration and is characterized by an inflammatory milieu and low oxygen tension (hypoxia). Negative interference with or prolongation of this fine-tuned initiation phase will ultimately lead to a delayed or incomplete healing such as non-unions which then requires an effective and gentle therapeutic intervention. Common reasons include a dysregulated immune response, immunosuppression or a failure in cellular adaptation to the inflammatory hypoxic milieu of the fracture gap and a reduction in vascularizing capacity by environmental noxious agents (e.g. rheumatoid arthritis or smoking). The hypoxia-inducible factor (HIF)-1α is responsible for the cellular adaptation to hypoxia, activating angiogenesis and supporting cell attraction and migration to the fracture gap. Here, we hypothesized that stabilizing HIF-1α could be a cost-effective and low-risk prevention strategy for fracture healing disorders. Therefore, we combined a well-known HIF-stabilizer - deferoxamine (DFO) - and a less known HIF-enhancer - macrophage migration inhibitory factor (MIF) - to synergistically induce improved fracture healing. Stabilization of HIF-1α enhanced calcification and osteogenic differentiation of MSCs in vitro. In vivo, only the application of DFO without MIF during the initial healing phase increased callus mineralization and vessel formation in a preclinical mouse-osteotomy-model modified to display a compromised healing. Although we did not find a synergistically effect of MIF when added to DFO, our findings provide additional support for a preventive strategy towards bone healing disorders in patients with a higher risk by accelerating fracture healing using DFO to stabilize HIF-1α.

Effect of Enamel Matrix Derivative and N-Acetyl Cysteine on Proliferation and Osteogenic Activity of Dental Pulp Stem Cells.

Successful bone regeneration often requires induction by signaling molecules. Enamel matrix derivative (EMD) is said to enhance initial phases of healing. N-acetyl cysteine (NAC) is a molecule assumed to enhance osteogenesis and induce osteoblastic differentiation. This study sought to compare effects of EMD and NAC on proliferation, mineralization, and enzymatic activity of dental pulp mesenchymal stem cells (DPSCs). DPSCs were cultured on mineralized bone allograft (MBA) powder. After 24 hours, EMD in concentrations of 10, 50, and 100 μg/mL and NAC in 5 mM concentration were added. Methyl thiazolyl tetrazolium (MTT) assay was used for cell proliferation assessment at 1, 2, and 3 days. Osteoblastic differentiation of DPSCs was evaluated at 30 days, by alizarin red staining and assessment of alkaline phosphatase (ALP) activity. Both EMD and NAC caused time-dependent reduction of cell proliferation compared with the negative control. Maximum proliferation of DPSCs was observed in the 10 μg/mL EMD group at all time points, whereas NAC caused higher ALP activity and mineralization of DPSCs compared with EMD. In vitro application of NAC, as a signaling molecule, may effectively enhance bone regeneration by the induction of mineralization and enzymatic activity, despite the resultant reduction in cell proliferation rate.

Sex Differences in Mesenchymal Stem Cell Therapy With Gelatin-Based Microribbon Hydrogels in a Murine Long Bone Critical-Size Defect Model.

Mesenchymal stem cell (MSC)-based therapy and novel biomaterials are promising strategies for healing of long bone critical size defects. Interleukin-4 (IL-4) over-expressing MSCs within a gelatin microribbon (µRB) scaffold was previously shown to enhance the bridging of bone within a critical size femoral bone defect in male Balb/c mice. Whether sex differences affect the healing of this bone defect in conjunction with different treatments is unknown. In this study, we generated 2-mm critical-sized femoral diaphyseal bone defects in 10–12-week-old female and male Balb/c mice. Scaffolds without cells and with unmodified MSCs were implanted immediately after the primary surgery that created the bone defect; scaffolds with IL-4 over-expressing MSCs were implanted 3 days after the primary surgery, to avoid the adverse effects of IL-4 on the initial inflammatory phase of fracture healing. Mice were euthanized 6 weeks after the primary surgery and femurs were collected. MicroCT (µCT), histochemical and immunohistochemical analyses were subsequently performed of the defect site. µRB scaffolds with IL-4 over-expressing MSCs enhanced bone healing in both female and male mice. Male mice showed higher measures of bone bridging and increased alkaline phosphatase (ALP) positive areas, total macrophages and M2 macrophages compared with female mice after receiving scaffolds with IL-4 over-expressing MSCs. Female mice showed higher Tartrate-Resistant Acid Phosphatase (TRAP) positive osteoclast numbers compared with male mice. These results demonstrated that sex differences should be considered during the application of MSC-based studies of bone healing.