Search

Unresolved inflammatory processes contribute to impaired healing in diabetic wounds, with increasing evidence implicating persistent pro-inflammatory macrophage polarization as a driver of chronic inflammation and delayed wound closure. Previous investigations aimed to uncover the role of regulatory RNAs in macrophage polarization and to understand how aberrant expression patterns contribute to wound healing impairment, with the goal of identifying novel therapeutic targets for promoting normal wound healing progression. In the Journal of Investigative Dermatology, Hu et al. reveal a role of the tumor suppressor, long noncoding RNA (lncRNA) Growth Arrest-Specific 5 (GAS5), in regulating macrophage polarization. Of note, their findings suggest that hyperglycemia induces overexpression of GAS5 which subsequently results in a greater production of the pro-inflammatory macrophage phenotype. Knockdown of GAS5 in diabetic wounds normalized healing time, highlighting the potential therapeutic value of targeting GAS5 for enhanced wound healing progression.

Acute respiratory distress syndrome (ARDS) is a devastating pulmonary disease with significant in-hospital mortality and is the leading cause of death in COVID-19 patients. Excessive leukocyte recruitment, unregulated inflammation, and resultant fibrosis contribute to poor ARDS outcomes. Nanoparticle technology with cerium oxide nanoparticles (CNP) offers a mechanism by which unstable therapeutics such as the anti-inflammatory microRNA-146a can be locally delivered to the injured lung without systemic uptake. In this study, we evaluated the potential of the radical scavenging CNP conjugated to microRNA-146a (termed CNP-miR146a) in preventing acute lung injury (ALI) following exposure to bleomycin. We have found that intratracheal delivery of CNP-miR146a increases pulmonary levels of miR146a without systemic increases, and prevents ALI by altering leukocyte recruitment, reducing inflammation and oxidative stress, and decreasing collagen deposition, ultimately improving pulmonary biomechanics., Graphical Abstract Bleomycin-induced lung injury produces a robust inflammatory response with increases in oxidative stress and pro-inflammatory markers such as IL-6. This leads to later remodeling with fibrosis and decreased lung function. Intratracheal delivery of cerium oxide nanoparticles (CNP) conjugated to microRNA-146a mitigates this initial inflammatory response, lowering later fibrosis and improving lung function.Unlabelled Image

Chronic inflammation plays a major role in impaired healing of diabetic wounds. Mounting evidence highlights the role of controlled, sequential polarization of macrophages in producing the appropriate progression through the stages of wound healing: inflammation (pro- inflammatory stage), proliferation and remodeling (regenerative stage). Non-coding RNAs, including microRNAs, maintain critical roles in regulating normal biological processes, such as wound healing; and are being explored as therapeutic targets for modulating dysfunction in disease states. Interestingly, microRNA-21 (miR-21) has a suggested role in the induction of pro-inflammatory and regenerative stages of healing, but clarity remains elusive on the specific mechanisms determining the direction miR-21 shifts wound healing processes. Findings by Liechty et al. in International Journal of Molecular Science indicate an important role of miR-21, in shaping the wound healing cascade by preferentially inducing M1-like (pro-inflammatory) polarization of macrophages in the early phase of diabetic wound healing. Persistent elevation of miR-21 is suggestive of sustained pro-inflammatory drive, and subsequent wound healing impairment, in the skin of diabetic murine models and diabetic human skin. Differences in the expression patterns of miR-21 during diabetic wound healing identifies the potentially critical role of therapeutic timing, for miR-21 based therapies, in driving positive outcomes for patients.

Acute respiratory distress syndrome (ARDS) is a devastating pulmonary disease with significant inhospital mortality and is the leading cause of death in COVID-19 patients. Potential therapies remain limited despite advancements in understanding ARDS pathophysiology. Excessive leukocyte recruitment, unregulated inflammation, and resultant fibrosis contribute to poor ARDS outcomes. In this study, we evaluated the potential of the radical scavenging cerium oxide nanoparticle (CNP) conjugated to the anti-inflammatory microRNA-146a (CNP-miR146a) to prevent acute lung injury (ALI) following exposure to bleomycin. We have found that CNP-miR146a can prevent ALI by altering leukocyte recruitment, reducing inflammation, and decreasing collagen deposition, ultimately improving pulmonary biomechanics.

A central feature of diabetic wounds is the persistence of chronic inflammation, which is partly due to the prolonged presence of pro-inflammatory (M1) macrophages in diabetic wounds. Persistence of the M1 macrophage phenotype and failure to transition to the regenerative or pro-remodeling (M2) macrophage phenotype plays an indispensable role in diabetic wound impairment, however, the mechanism underlying this relationship remains unclear. Recently, microRNAs have been shown to provide an additional layer of regulation of gene expression. In particular, microRNA-21 (miR-21) is essential for an inflammatory immune response. We hypothesize that miR-21 plays a role in regulating inflammation by promoting M1 macrophage polarization and the production of reactive oxygen species (ROS). To test our hypothesis, we employed an in vivo mouse skin wound model in conjunction with an in vitro mouse model to assess miR-21 expression and macrophage polarization. First, we found that miR-21 exhibits a distinct expression pattern in each phase of healing in diabetic wounds. MiR-21 abundance was higher during early and late phases of wound repair in diabetic wounds, while it was significantly lower in the middle phase of wounding (at days 3 and 7 following wounding). In macrophage cells, M1 polarized macrophages exhibited an upregulation of miR-21, as well as the M1 and pro-inflammatory markers IL-1b, TNFa, iNos, IL-6, and IL-8. Overexpression of miR-21 in macrophage cells resulted in an upregulation of miR-21 and also increased expression of the M1 markers IL-1b, TNFa, iNos, and IL-6. Furthermore, hyperglycemia induced NOX2 expression and ROS production through the HG/miR-21/PI3K/NOX2/ROS signaling cascade. These findings provide evidence that miR-21 is involved in the regulation of inflammation. Dysregulation of miR-21 may explain the abnormal inflammation and persistent M1 macrophage polarization seen in diabetic wounds.

A central feature of diabetic (Db) wounds is the persistence of chronic inflammation, which is partly due to the prolonged presence of proinflammatory (M1) macrophages. Using in vivo and in vitro analyses, we have tested the hypothesis that long noncoding RNA GAS5 is dysregulated in Db wounds. We have assessed the contribution of GAS5 to the M1 macrophage phenotype, as well as the functional consequences of knocking down its expression. We found that expression of GAS5 is increased significantly in Db wounds and in cells isolated from Db wounds. Hyperglycemia induced GAS5 expression in macrophages in vitro. Overexpression of GAS5 in vitro promoted macrophage polarization toward an M1 phenotype by upregulating signal transducer and activator of transcription 1. Of most significance in our judgment, GAS5 loss-of-function enhanced Db wound healing. These data indicate that the relative level of long noncoding RNA GAS5 in wounds plays a key role in the wound healing response. Reductions in the levels of GAS5 in wounds appeared to enhance healing by promoting transition of M1 macrophages to M2 macrophages. Thus, our results suggest that targeting long noncoding RNA GAS5 may provide a therapeutic intervention for correcting impaired Db wound healing.

The recognition of dysregulated immunity and abnormal healing processes in diabetes has driven a growth in research on novel therapeutics for the treatment of diabetic skin wounds. Two targets of interest include mesenchymal stem cells (MSCs) and microRNA (miRNA). MSCs are multipotent cells with tissue regeneration capabilities that influence wound healing through multiple pathways, including through correction of dysregulated miRNA expression in inflammatory conditions like diabetes. MiRNA are small molecules that regulate various cellular processes, including ones critical to wound healing. In this chapter, we will summarize how MSCs play a role in wound healing, how miRNA are dysregulated in diabetic wounds, and how MSCs correct miRNA dysregulation.

Background In contrast to adults, the fetal response to myocardial infarction (MI) is regenerative, requiring the recruitment of cardiac progenitor cells to replace infarcted myocardium. Macrophage contribution to tissue repair depends on their phenotype: M1 are proinflammatory and initiate angiogenesis; M2a are profibrotic and contribute to blood vessels maturation; and M2c are proremodeling and proangiogenesis. The goal of the present study was to expand on this work by examining cardiac progenitor cells recruitment, and the role of macrophages in promoting angiogenesis and cardiac regeneration in the fetal heart after MI. Methods Fetal and adult sheep underwent MI and were sacrificed 3 or 30 days after MI. Some fetal hearts received stromal cell-derived factor-1α-inhibitor treatment. The microvasculature was evaluated by micro–computed tomography, gene expression was evaluated by real-time polymerase chain reaction, and vessels counts were evaluated by immunohistochemistry. Results Micro–computed tomography analysis showed restoration of microvasculature in fetal hearts after MI. Vascular endothelial growth factor-α increased, and the expression of tissue markers associated with the M1, M2a, and M2c macrophage phenotypes were elevated at day 3 after MI, but returned to baseline by 30 days after MI. In contrast, adult hearts after MI exhibited low vascular endothelial growth factor-α and persistent upregulation of all macrophage markers, consistent with prolonged inflammation, fibrosis, and remodeling. Inhibition of stromal cell-derived factor-1α in fetal infarcts prevented angiogenesis, decreased vascular endothelial growth factor-α, and was associated with a sustained increase in M1, M2a, and M2c markers after MI. Conclusions Changes in angiogenesis and macrophage phenotype-related gene expression after MI are important for the fetal regenerative response to MI and are mediated at least in part by cardiac progenitor cells recruitment.

One of the major complications in diabetes is impaired wound healing. Unfortunately, effective therapies are currently lacking. Epithelial to mesenchymal transition (EMT) is a critical process involved in cutaneous wound healing. In response to injury, EMT is required to activate and mobilize stationary keratinocytes in the skin toward the wound bed, which allows for re-epithelialization. This process is stalled in diabetic wounds. In this study, we investigate the role of long non-coding RNA (lncRNA), MALAT1, in transforming growth factor beta 1(TGF-β1)-induced EMT of human keratinocyte (HaCaT) cells. Initially, we detected MALAT1 and TGF-β1 expression in non-diabetic and diabetic wounds and found that these expression are significantly up-regulated in diabetic wounds. Then, HaCaT cells were cultured and exposed to TGF-β1. The EMT of HaCaT cells were confirmed by the increased expression of CDH2, KRT10, and ACTA2, in addition to the down-regulation of CDH1. Knockdown of MALAT1 was achieved by transfecting a small interfering RNA (SiRNA). MALAT1 silencing attenuates TGFβ1-induced EMT. Mechanistically, MALAT1 is involved in TGF-β1 mediated EMT through significantly induced ZEB1 expression, a critical transcription factor for EMT. In summary, lncRNA MALAT1 is involved in TGFβ1-induced EMT of human HaCaT cells and provides new understanding for the pathogenesis of diabetic wounds.

Impaired diabetic wound healing is associated with a dermal extracellular matrix protein profile favoring proteolysis; within the healing diabetic wound, this is represented by an increase in activated matrix metalloproteinase (MMPs). Treatment of diabetic wounds with mesenchymal stem cells (MSCs) has been shown to improve wound healing; however, there has not yet been an assessment of their ability to correct dysregulation of MMPs in diabetic wounds. Furthermore, there has been no prior assessment of the role of microRNA29b (miR-29b), an inhibitory regulatory molecule that targets MMP-9 mRNA. Using in vitro models of fibroblast coculture with MSCs and in vivo murine wound healing models, we tested the hypothesis that MSCs correct dysregulation of MMPs in a microRNA-29b-dependent mechanism. In this study, we first demonstrated that collagen I and III protein content is significantly reduced in diabetic wounds, and treatment with MSCs significantly improves collagen I content in both nondiabetic and diabetic wounds. We then found that MMP-9 gene expression and protein content were significantly upregulated in diabetic wounds, indicating elevated proteolysis. Treatment with MSCs resulted in a decrease in MMP-9 gene expression and protein content level in diabetic wounds 3 and 7 days after wounding. Zymographic analysis indicated that MSC treatment also decreased the amount of activated MMP-9 present in diabetic wounds. Furthermore, miR-29b expression was inversely associated with MMP-9 gene expression; miR-29b expression was decreased in diabetic wounds and diabetic fibroblast. Following treatment of diabetic wounds with MSCs, as well as in diabetic fibroblasts cocultured with MSCs, miR-29b was significantly increased. These findings suggest a potential mechanism through which MSCs enhance diabetic wound healing by improving collagen I content in diabetic wounds through decreasing MMP-9 expression and increasing miR-29b expression.

Background and Hypothesis: Impaired wound healing is a serious complication of diabetes and accounts for over 70,000 amputations annually in the United States. Accumulating evidence suggests that wounds with poor healing process display persistently elevated protease activity. Here we tested the hypothesis that genetic knockout or pharmacological inhibition of cathepsin K, a cysteine protease with potent collagenolytic and elastolytic activity, accelerates wound closure in diabetic mice. Methods: Diabetes was induced in cathepsin K knockout (Ctsk-/-) and wild type litter-mates by intraperitoneal injection of streptozotocin (STZ, 120 mg/Kg). Two weeks following STZ injection, a full thickness 8-mm excisional wound was created on the dorsum of the mice. In a separate set of experiments, excisional skin wounds were created in genetically diabetic (db+/db+) and their normoglycemic litter-mates. The wounds were treated with cathepsin K inhibitor II (0.35μg/d on days 0, 3, and 5), or vehicle, given as intradermal injections along the circumference of the wound. Wound healing was evaluated by measuring the wound closure rate, CD31 expression, and histological analysis. Results: In the STZ-induced diabetic model, wounds in the cathepsin K-knockout mice closed significantly earlier than the vehicle-treated wounds. Similarly, pharmacological inhibition of cathepsin K in db/db mice resulted in near complete resolution of the wound in 22 days compared to about 29 days in vehicle-treated mice. Histological evaluations demonstrated that topical delivery of cathepsin K inhibition resulted in higher levels of collagen deposition and increased angiogenesis. In an in vitro scratch-assay using cultured human fibroblasts, cell migration, which was significantly impaired by high-glucose concentrations, was restored by cathepsin K inhibitor-II. Conclusion: Cathepsin K may represent a potential treatment-target to facilitate diabetic wound healing. Disclosure R. Guo: None. L. Zhang: None. A. Thakar: None. T.E. Brown: None. J. Ren: None. C. Zgheib: None. J. Xu: None. K.W. Liechty: Consultant; Spouse/Partner; Cell research. S. Nair: None. Funding National Institute of General Medical Sciences (2P20GM1034320); University of Wyoming

BackgroundStem cell therapy is the next generation a well-established technique. Cell therapy with mesenchymal stem cells (MSC) has been demonstrated to enhance wound healing in diabetic mice, at least partly due to improved growth factor production. However, it is unclear whether MSC can biomechanically affect wound closure. Utilizing the well-established cell-populated collagen gel contraction model we investigated the interactions between MSC and the extracellular matrix.MethodsMurine fetal liver-derived Mesenchymal Stem Cells (MSCs) or fetal Dermal Fibroblasts (DFs) were cultured in cell-populated collagen gels (CPCGs). The effect of cell density, conditioned media, growth factors (TGF-B1, FGF, PDGF-BB), cytoskeletal disruptors (colchicine, cytochalasin-D), and relative hypoxia on gel contraction were evaluated. Finally, we also measured the expression of integrin receptors and some growth factors by MSCs within the contracting gels.ResultsOur results show that at different densities, MSCs induced a higher gel contraction compared to DFs. Higher cell density resulted in faster and more complete contraction of CPCGs. Cytoskeletal inhibitors either inhibited or prevented MSC-mediated contraction in a dose dependent fashion. Growth factors, conditioned media from both MSC and DF, and hypoxia all influenced CPCG contraction.DiscussionThe results suggest that MSCs are capable of directly contributing to wound closure through matrix contraction, and they are more effective than DF. In addition, this study demonstrates the importance of how other factors such as cell concentration, cytokines, and oxygen tension can provide potential modulation of therapies to correct wound healing impairments.

Diabetic skin has impaired wound healing properties following injury. We have further shown that diabetic skin has weakened biomechanical properties at baseline. We hypothesize that the biomechanical properties of diabetic skin decline during the progression of the diabetic phenotype, and that this decline is due to the dysregulation of miR-29a, resulting in decreased collagen content. We further hypothesize that treatment with mesenchymal stem cells (MSCs) may improve diabetic wound healing by correction of the dysregulated miR-29a expression. We analyzed the biomechanical properties, collagen gene expression, collagen protein production, and miR-29a levels in skin harvested from 6 to 18 week old mice during the development of the diabetic phenotype. We also examined the correction of these impairments by both MSC treatment and the inhibition of miR-29a. Diabetic skin demonstrated a progressive impairment of biomechanical properties, decreased collagen content, and increased miR-29a levels during the development of the diabetic phenotype. MSC treatment decreased miR-29a levels, increased collagen content, and corrected the impaired biomechanical properties of diabetic skin. Additionally, direct inhibition of miR-29a also increased collagen content in diabetic skin. This decline in the biomechanical properties of diabetic skin during the progression of diabetes may increase the susceptibility of diabetic skin to injury and miR-29a appears to play a key role in this process.

Numerous studies have investigated the link between oral contraceptives and risk of ulcerative colitis (UC), but the results have been controversial. We systematically reviewed all relevant published studies and evaluated the association between the use of oral contraceptives and the development of UC by meta-analysis. Databases including PubMed, EMbase, CNKI and WanFang data were thoroughly searched from inception to September 2018 to collect the studies on the correlation between oral contraceptives and the risk of UC. The studies were screened according to the inclusion and exclusion criteria by two researchers independently, and the data were extracted and the quality was evaluated. Meta-analysis was performed using Stata 13.0 software. There were 12 studies involving 303,340 participants that reported on the association between oral contraceptives and UC. The pooled odds ratio (OR) of UC in oral contraceptive users was 1.25 [95% confidence interval (CI) 1.04–1.51, p = 0.02]. The risk was significant in the current oral contraceptive users (OR 1.49, 95% CI 1.12–1.96, p = 0.005) whereas the past oral contraceptive use was not significantly associated with UC (OR 1.17, 95% CI 0.95–1.43, p = 0.141). This study provides evidence of an association between the use of oral contraceptives and the onset risk of UC. The study also shows that the risk for patients who stop using the oral contraceptives was decreased. These findings may be used as important reference for the use of oral contraceptives and the management of UC patients.

BACKGROUND: Diabetic wounds have become one of the most challenging public health issues of the 21st century, yet there is no effective treatment available. We have previously shown that the diabetic wound healing impairment is associated with increased inflammation and decreased expression of the regulatory microRNA miR-146a. We have conjugated miR-146a to cerium oxide nanoparticles (CNP-miR146a) to target reactive oxygen species (ROS) and inflammation. This study aimed to evaluate the consequences of CNP-miR146a treatment of diabetic wounds. STUDY DESIGN: Eight-millimeter wounds were created on the dorsal skin of Db/Db mice and treated with PBS or differing concentrations of CNP-mir146a (1; 10; 100; or 1,000 ng) at the time of wounding. Rate of wound closure was measured until the wounds were fully healed. At 4 weeks post-healing, a dumbbell-shaped skin sample was collected, with the healed wound in the center, and an Instron 5942 testing unit was used to measure the maximum load and modulus. RESULTS: Our data showed that diabetic wounds treated with PBS or 1 ng CNP-miR146a took 18 days to heal. Treatment with 10, 100, or 1,000 ng of CNP+miR-146a effectively enhanced healing, and wounds were fully closed at day 14 post-wounding. The healed skin from the CNP-miR146a-treated group showed a trend of improved biomechanical properties (increased maximum load and modulus), however it did not reach significance. CONCLUSIONS: We found that a 100-ng dose of CNP-miR146a improved diabetic wound healing and did not impair the biomechanical properties of the skin post-healing. This nanotechnology-based therapy is promising, and future studies are warranted to transfer this therapy to clinical application. (J Am Coll Surg 2019;228:107–115. 2018 by the American College of Surgeons. Published by Elsevier Inc. All rights reserved.)

Background Global extracellular matrix (ECM)-related gene expression is decreased after myocardial infarction (MI) in fetal sheep when compared with adult sheep. Transforming growth factor (TGF)-β1 is a key regulator of ECM; therefore we hypothesize that TGF-β1 is differentially expressed in adult and fetal infarcts after MI. Methods Adult and fetal sheep underwent MI via ligation of the left anterior descending coronary artery. Expression of TGF-β1 and ECM-related genes was evaluated by ovine-specific microarray and quantitative polymerase chain reaction. Fibroblasts from the left ventricle of adult and fetal hearts were treated with TGF-β1 or a TGF-β1 receptor inhibitor (LY36497) to evaluate the effect of TGF-β1 on ECM-related genes. Results Col1a1, col3a1, and MMP9 expression were increased in adult infarcts 3 and 30 days after MI but were upregulated in fetal infarcts only 3 days after MI. Three days after MI elastin expression was increased in adult infarcts. Despite upregulation in adult infarcts both 3 and 30 days after MI, TGF-β1 was not upregulated in fetal infarcts at any time point. Inhibition of the TGF-β1 receptor in adult cardiac fibroblasts decreased expression of col1a1, col3a1, MMP9, elastin, and TIMP1, whereas treatment of fetal cardiac fibroblasts with TGF-β1 increased expression of these genes. Conclusions TGF-β1 is increased in adult infarcts compared with regenerative, fetal infarcts after MI. Although treatment of fetal cardiac fibroblasts with TGF-β1 conveys an adult phenotype, inhibition of TGF-β1 conveys a fetal phenotype to adult cardiac fibroblasts. Decreasing TGF-β1 after MI may facilitate myocardial regeneration by "fetalizing" the otherwise fibrotic, adult response to MI.

Diabetic skin wounds lack the ability to heal properly and constitute a major and significant complication of diabetes. Nontraumatic lower extremity amputations are the number one complication of diabetic skin wounds. The complexity of their pathophysiology requires an intervention at many levels to enhance healing and wound closure. Stem cells are a promising treatment for diabetic skin wounds as they have the ability to correct abnormal healing. Stem cell factor (SCF), a chemokine expressed in the skin, can induce stem cells migration, however the role of SCF in diabetic skin wound healing is still unknown. We hypothesize that SCF would correct the impairment and promote the healing of diabetic skin wounds. Our results show that SCF improved wound closure in diabetic mice and increased HIF-1α and vascular endothelial growth factor (VEGF) expression levels in these wounds. SCF treatment also enhanced the migration of red fluorescent protein (RFP)-labeled skin stem cells via in utero intra-amniotic injection of lenti-RFP at E8. Interestingly these RFP+ cells are present in the epidermis, stain negative for K15, and appear to be distinct from the already known hair follicle stem cells. These results demonstrate that SCF improves diabetic wound healing in part by increasing the recruitment of a unique stem cell population present in the skin.

Diabetic skin has impaired wound healing properties following injury. We have further shown that diabetic skin has weakened biomechanical properties at baseline. We hypothesize that the biomechanical properties of diabetic skin decline during the progression of the diabetic phenotype, and that this decline is due to the dysregulation of miR-29a, resulting in decreased collagen content. We further hypothesize that treatment with mesenchymal stem cells (MSCs) may improve diabetic wound healing by correction of the dysregulated miR-29a expression. We analyzed the biomechanical properties, collagen gene expression, collagen protein production, and miR-29a levels in skin harvested from 6 to 18 week old mice during the development of the diabetic phenotype. We also examined the correction of these impairments by both MSC treatment and the inhibition of miR-29a. Diabetic skin demonstrated a progressive impairment of biomechanical properties, decreased collagen content, and increased miR-29a levels during the development of the diabetic phenotype. MSC treatment decreased miR-29a levels, increased collagen content, and corrected the impaired biomechanical properties of diabetic skin. Additionally, direct inhibition of miR-29a also increased collagen content in diabetic skin. This decline in the biomechanical properties of diabetic skin during the progression of diabetes may increase the susceptibility of diabetic skin to injury and miR-29a appears to play a key role in this process.

Diabetic skin wounds lack the ability to heal properly and constitute a major and significant complication of diabetes. Nontraumatic lower extremity amputations are the number one complication of diabetic skin wounds. The complexity of their pathophysiology requires an intervention at many levels to enhance healing and wound closure. Stem cells are a promising treatment for diabetic skin wounds as they have the ability to correct abnormal healing. Stem cell factor (SCF), a chemokine expressed in the skin, can induce stem cells migration, however the role of SCF in diabetic skin wound healing is still unknown. We hypothesize that SCF would correct the impairment and promote the healing of diabetic skin wounds. Our results show that SCF improved wound closure in diabetic mice and increased HIF-1α and vascular endothelial growth factor (VEGF) expression levels in these wounds. SCF treatment also enhanced the migration of red fluorescent protein (RFP)-labeled skin stem cells via in utero intra-amniotic injection of lenti-RFP at E8. Interestingly these RFP+ cells are present in the epidermis, stain negative for K15, and appear to be distinct from the already known hair follicle stem cells. These results demonstrate that SCF improves diabetic wound healing in part by increasing the recruitment of a unique stem cell population present in the skin.

Mesenchymal stem cells are multipotent cells and thus potential building blocks for regenerating lost tissue. MicroRNAs, or miRNAs, are critical for regulating interactions essential for skin and epithelial appendage morphogenesis. They affect the three phases of wound healing—inflammation, proliferation, and remodeling—each of which involves changes in the expression of specific miRNAs that affect wound inflammatory response, reepithelialization, angiogenesis, and tissue remodeling. Abnormal expression leads to abnormal healing. This chapter discusses The functions of miRNAs in wound healing.

Type 2 diabetes mellitus is a complex, systemic metabolic disease characterized by insulin resistance and resulting hyperglycemia, which is associated with impaired wound healing. The clinical complications associated with hyperglycemia are attributed, in part, to the increased production of reactive oxygen species (ROS). Recent studies revealed that long non-coding RNAs (lncRNAs) play important regulatory roles in many biological processes. Specifically, lncRNA Lethe has been described as exhibiting an anti-inflammatory effect by binding to the p65 subunit of NFκB and blocking its binding to DNA and the subsequent activation of downstream genes. We therefore hypothesize that dysregulation of Lethe's expression plays a role in hyperglycemia-induced ROS production. To test our hypothesis, we treated RAW264.7 macrophages with low glucose (5 mM) or high glucose (25 mM) for 24h. High glucose conditions significantly induced ROS production and NOX2 gene expression in RAW cells, while significantly decreasing Lethe gene expression. Overexpression of Lethe in RAW cells eliminated the increased ROS production induced by high glucose conditions, while also attenuating the upregulation of NOX2 expression. Similar results was found also in non-diabetic and diabetic primary macrophage, bone marrow derived macrophage (BMM). Furthermore, overexpression of Lethe in RAW cells treated with high glucose significantly reduced the translocation of p65-NFkB to the nucleus, which resulted in decreased NOX2 expression and ROS production. Interestingly, these findings are consistent with the decreased Lethe gene expression and increased NOX2 gene expression observed in a mouse model of diabetic wound healing. These findings provide the first evidence that lncRNA Lethe is involved in the regulation of ROS production in macrophages through modulation of NOX2 gene expression via NFκB signaling. Moreover, this is the first report to describe a role of lncRNAs, in particular Lethe, in impaired diabetic wound healing. Further studies are warranted to determine if correction of Lethe expression in diabetic wounds could improve healing.

Aim: This study aimed to investigate the specificity and potency of curcumin derivative 64PH in inhibiting the proliferation of HepG2 human hepatoma cells in vitro. Methods: Various concentrations of 64PH were administrated to HepG2 hepatoma cells and HL7702 hepatic cells. The viability of cells was evaluated by methyl thiazolyl tetrazolium assay. The concentration-inhibition rates in the two cell lines were calculated, and the accumulation normal distribution function was adopted to fit their rate curves. The differences of the rates between the two cells were observed on the 3rd day of 64PH treatment. The maximum difference and the 95% credibility interval of the corresponding 64PH concentration were evaluated. Results: 64PH inhibited the proliferation of HepG2 and HL7702 cells in vitro. To fit the concentration-effect curves on the 3rd day, the determination coefficients (γ2) were more than 0.99, the half maximal inhibitory concentration (IC50) was 3.07 and 4.28 μg/mL of 64PH, respectively, and their ratio was 1.39. To fit the normal distribution function of the differences of concentration-inhibition rates between HepG2 and HL7702 cells (s2 = 0.9861), the maximum difference of inhibition rates was 33.58%, and the corresponding concentration of 64PH and the 95% credibility interval were 2.65 and 3.52 μg/mL, respectively. Conclusion: In vitro, HepG2 cells are more sensitive than HL7702 cells due to the presence of 64PH. The inhibition of cell proliferation induced by 64PH is stronger in HepG2 than in HL7702 at concentrations between 2.65 and 3.52 μg/mL. 64PH has the potential to be a therapeutic approach in hepatocellular carcinoma and to achieve the desired efficacy and safety.