Sae Hee Ko

Adipose-derived Stromal Cells Overexpressing Vascular Endothelial Growth Factor Accelerate Mouse Excisional Wound Healing

Angiogenesis is essential to wound repair, and vascular endothelial growth factor (VEGF) is a potent factor to stimulate angiogenesis. Here, we examine the potential of VEGF-overexpressing adipose-derived stromal cells (ASCs) for accelerating wound healing using nonviral, biodegradable polymeric vectors. Mouse ASCs were transfected with DNA plasmid encoding VEGF or green fluorescent protein (GFP) using biodegradable poly (β-amino) esters (PBAE). Cells transfected using Lipofectamine 2000, a commercially available transfection reagent, were included as controls. ASCs transfected using PBAEs showed enhanced transfection efficiency and 12-15-fold higher VEGF production compared with cells transfected using Lipofectamine 2000 (*P < 0.05). When transplanted into a mouse wild-type excisional wound model, VEGF-overexpressing ASCs led to significantly accelerated wound healing, with full wound closure observed at 8 days compared to 10-12 days in groups treated with ASCs alone or saline control (*P < 0.05). Histology and polarized microscopy showed increased collagen deposition and more mature collagen fibers in the dermis of wound beds treated using PBAE/VEGF-modified ASCs than ASCs alone. Our results demonstrate the efficacy of using nonviral-engineered ASCs to accelerate wound healing, which may provide an alternative therapy for treating many diseases in which wound healing is impaired.

The role of stem cells in cutaneous wound healing: what do we really know?

Summary: Wound repair is a complex process involving the orchestrated interaction of multiple growth factors, cytokines, chemokines, and cell types. Dysregulation of this process leads to problems such as excessive healing in the form of keloids and hypertrophic scars and chronic, nonhealing wounds. These issues have broad global implications. Stem cells offer enormous potential for enhancing tissue repair and regeneration following injury. The rapidly developing fields of stem cell biology and skin tissue engineering create translational opportunities for the development of novel stem cell–based wound-healing therapies.

Antimycotic Ciclopirox Olamine in the Diabetic Environment Promotes Angiogenesis and Enhances Wound Healing

Diabetic wounds remain a major medical challenge with often disappointing outcomes despite the best available care. An impaired response to tissue hypoxia and insufficient angiogenesis are major factors responsible for poor healing in diabetic wounds. Here we show that the antimycotic drug ciclopirox olamine (CPX) can induce therapeutic angiogenesis in diabetic wounds. Treatment with CPX in vitro led to upregulation of multiple angiogenic genes and increased availability of HIF-1α. Using an excisional wound splinting model in diabetic mice, we showed that serial topical treatment with CPX enhanced wound healing compared to vehicle control treatment, with significantly accelerated wound closure, increased angiogenesis, and increased dermal cellularity. These findings offer a promising new topical pharmacologic therapy for the treatment of diabetic wounds.

Discussion. TGF-beta1 RNA interference in mouse primary dura cell culture: downstream effects on TGF receptors, FGF-2, and FGF-R1 mRNA levels.

N calvarial development is dependent on coordinated growth between the underlying brain and overlying cranial bone plates. Cranial sutures form between the developing bone plates as specialized joint structures. Perturbations in the complex interactions among the brain, dura mater, suture mesenchyme, and osteogenic fronts during development can lead to the premature fusion of cranial sutures, or craniosynostosis. The murine model has been instrumental in the study of craniosynostosis because the murine posterior frontal suture fuses (analogous to the metopic suture in humans) in the first 2 weeks of life, whereas all other cranial sutures remain patent.1,2 Investigations using the murine model have revealed that the underlying dura mater and its paracrine signaling are critical in determining the fate of the overlying suture. A number of molecules are known to mediate this communication, including transforming growth factor (TGF), fibroblast growth factors (FGF), bone morphogenetic proteins, and bone morphogenetic protein antagonists.3,4 Dr. Gosain et al. present potential utility of RNA interference (RNAi) to alter murine dura cytokines responsible for suture fusion in vitro. The authors optimized the conditions for transient transfection of a pool of small interfering RNA (siRNA) targeted to TGF1 using a mouse dura cell culture model. With the optimal dose of siRNA, TGF1 mRNA expression was reduced to 10 percent of the control up to 10 days following transfection. Although TGFR1 mRNA expression was unaffected by the TGF1 siRNA, TGFR2 mRNA expression showed a transient inhibition after siRNA transfection. In addition, transfection with TGF1 siRNA led to a transient (4 days) inhibition of FGF-2 and FGF-R1 mRNA expression. Several studies have demonstrated that regional variation in the paracrine signals from dura mater is responsible for suture patency.5,6 Because these experiments described by Gosain et al. were carried out in vitro using primary cell culture derived from pooled dura layer of mouse calvaria as opposed to cells derived from a single region of dura, clinical translation of this approach is not apparent. However, this article adds to the growing literature demonstrating that siRNA technology has outstanding potential to perform loss-of-function studies in cultured cells and to provide novel therapeutic approaches for human disease. Fire et al. published a landmark article in 1998 reporting the ability of double-stranded RNA to silence gene expression in the nematode worm Caenorhabditis elegans.7 Less than a decade after their seminal publication, they won the Nobel Prize in Physiology or Medicine, highlighting the importance of this discovery.8 RNAi is a fundamental pathway in eukaryotic cells in which sequence-specific siRNA is able to bind and cleave complementary (target) mRNAs.9 RNAi is triggered by double-stranded RNA, which is cleaved into fragments known as siRNA by the enzyme Dicer.10 A specialized protein known as the RNAinduced silencing complex then unwinds the siRNA and joins with antisense strand.11 The activated RNA-induced silencing complex, which contains the antisense strand, selectively binds and degrades mRNA that is complementary to the antisense strand.12 In the past decade, billions of dollars have been invested in the therapeutic application of gene silencing in humans.13 Today,