Novel antisense oligonucleotides targeting TGF-beta inhibit in vivo scarring and improve surgical outcome

Therapeutic potential of Pirfenidone for treating equine corneal scarring

OBJECTIVE

To evaluate the safety and efficacy of Pirfenidone (PFD) in the treatment of equine corneal fibrosis using an in vitro model.

METHODS

Healthy donor equine corneas were collected and used to generate primary equine corneal fibroblasts (ECFs) by growing cultures in minimal essential medium supplemented with 10% fetal bovine serum. Equine corneal myofibroblasts (ECMs), used as a model of equine corneal fibrosis, were produced by growing ECF cultures in serum-free medium containing transforming growth factor β1 (1 ng/mL). Trypan blue viability assays and changes in ECF morphology were utilized to determine the optimal PFD dose for this in vitro model. Trypan blue viability, phase-contrast microscopy, and TUNEL assays were used to evaluate the cytotoxicity of PFD. Scratch and MTT assays were used to evaluate the effect of PFD on cellular migration and proliferation. Real-time PCR, immunoblot analysis, and immunocytochemistry were employed to determine the efficacy of PFD to inhibit ECM formation in vitro.

RESULTS

Topical PFD application at 200 μg/mL successfully decreased αSMA expression when compared to the TGFβ1 only treatment group (P < 0.01). PFD application ≤ 200 μg/mL did not affect ECF phenotype or cellular viability and did not result in significant cytotoxicity.

CONCLUSIONS

Pirfenidone safely and effectively inhibits TGFβ1-induced equine corneal fibrosis in vitro. In vivo studies are warranted.

Aptamer-based therapeutics of the past, present and future: from the perspective of eye-related diseases

Aptamers have emerged as a novel and powerful class of biomolecules with an immense untapped potential. The ability to synthesise highly specific aptamers against any molecular target make them a vital cog in the design of effective therapeutics for the future. However, only a minutia of the enormous potential of this dynamic class of molecule has been exploited. Several aptamers have been studied for the treatment of eye-related disorders, and one such strategy has been successful in therapy. This review gives an account of several eye diseases and their regulatory biomolecules where other nucleic acid therapeutics have been attempted with limited success and how aptamers, with their exceptional flexibility to chemical modifications, can overcome those inherent shortcomings.

siRNA-targeting transforming growth factor-β type I receptor reduces wound scarring and extracellular matrix deposition of scar tissue

Hypertrophic scarring is related to persistent activation of transforming growth factor-β (TGF-β)/Smad signaling. In the TGF-β/Smad signaling cascade, the TGF-β type I receptor (TGFBRI) phosphorylates Smad proteins to induce fibroblast proliferation and extracellular matrix deposition. In this study, we inhibited TGFBRI gene expression via TGFBRI small interfering RNA (siRNA) to reduce fibroblast proliferation and extracellular matrix deposition. Our results demonstrate that downregulating TGFBRI expression in cultured human hypertrophic scar fibroblasts significantly suppressed cell proliferation and reduced type I collagen, type III collagen, fibronectin, and connective tissue growth factor (CTGF) mRNA, and type I collagen and fibronectin protein expression. In addition, we applied TGFBRI siRNA to wound granulation tissue in a rabbit model of hypertrophic scarring. Downregulating TGFBRI expression reduced wound scarring, the extracellular matrix deposition of scar tissue, and decreased CTGF and α-smooth muscle actin mRNA expression in vivo. These results suggest that TGFBRI siRNA could be applied clinically to prevent hypertrophic scarring.

Triple combination of siRNAs targeting TGFβ1, TGFβR2, and CTGF enhances reduction of collagen I and smooth muscle actin in corneal fibroblasts

PURPOSE

Transforming growth factor β1 (TGFβ1), TGFβ receptor (TGFβR2), and connective tissue growth factor (CTGF) are key regulators of fibrosis in the cornea and in other tissues, including liver, skin, and kidney. We developed an antifibrotic treatment targeting these three critical scarring genes by using a combination of small interfering RNAs (siRNAs) and assessed its effect on downstream scarring genes, collagen I, and α smooth muscle actin (SMA).

METHODS

Up to six individual siRNAs for each of the three target gene mRNAs were transfected into cultures of rabbit corneal fibroblasts at concentrations from 15 to 90 nM. The knockdown of target gene proteins was measured by ELISA, and the two most effective siRNAs were tested in dual combinations. Knockdown percentages of both individual and dual siRNA combinations were analyzed for synergy by using combination index to predict "effective" and "ineffective" triple siRNA combinations. Effects of both triple siRNA combinations on target and downstream mRNAs were measured by using quantitative RT-PCR, and levels of SMA protein were assessed by immunohistochemistry.

RESULTS

Single and dual siRNA combinations produced a wide range of protein knockdown of target genes (5%-80%). The effective triple siRNA combination significantly reduced mRNA levels of target genes (>80%) and downstream scarring genes (>85%), and of SMA protein (>95%), and significantly reduced cell migration without reducing cell viability.

CONCLUSIONS

Simultaneous targeting of TGFβ1, TGFβR2, and CTGF genes by effective triple siRNA combination produced high knockdown of target and downstream scarring genes without cell toxicity, which may have clinical applications in reducing corneal fibrosis and scarring in other tissues.

RNA Interference Targeting Connective Tissue Growth Factor Inhibits the Transforming Growth Factor- β 2 Induced Proliferation in Human Tenon Capsule Fibroblasts

Purpose. This study was to determine the effect of CTGF-small interfering RNA (siRNA) on TGF- β 2-induced proliferation in human Tenon capsule fibroblasts (HTFs). Methods. HTFs were transfected with four of CTGF-siRNAs separately for screening of gene silencing efficacy that was determined by transcript level measured by quantitative real-time PCR (qRT-PCR). Recombinant TGF- β 2 was added into the culture to stimulate the proliferation of HTFs. The gene silencing efficacy of the siRNAs was evaluated by qRT-PCR and immunofluorescence of CTGF transcript and protein levels. The viability of HTFs was determined by cell counting kit-8 (CCK-8). FCM was used to assess cell cycle after CTGF-siRNA transfection. Results. The expression of CTGF and proliferation of HTFs were increased significantly by TGF- β 2 stimulation. The transfection of CTGF-siRNA abolished the upregulation of CTGF and cell proliferation induced by TGF- β 2. The analysis of cell cycle indicated that CTGF-siRNA treatment stimulated cells from S phase to G0/G1 phase in comparison with the inverse physiologic function of TGF- β 2. Conclusion. CTGF targeting siRNA could effectively suppress the expression of CTGF and attenuate the proliferation of HTFs. The siRNA approach may provide a therapeutic option for eliminating filtration bleb scarring after glaucoma filtration surgery (GFS).

Altered TGF-β signaling in fetal fibroblasts: what is known about the underlying mechanisms?

Scarless wound healing is a unique and intrinsic capacity of the fetal skin that is not fully understood. Further insight into the underlying mechanisms of fetal wound healing may lead to new therapeutic approaches promoting adult scarless wound healing. Differences between fetal and adult wound healing are found in the extracellular matrix, the inflammatory reaction and the levels of growth factors present in the wound. This review focuses specifically on transforming growth factor β (TGF-β), as this growth factor is prominently involved in wound healing and fibroblast-to-myofibroblast differentiation. Although fetal fibroblasts do respond to TGF-β, they lack a proliferative and a contractile response and display short-lived myofibroblast differentiation, autocrine response, and collagen up-regulation in comparison with adult fibroblasts. Curiously, prolonged TGF-β activation is associated with fibrosis, and therefore, this short-lived response in fetal fibroblasts might contribute to scarless healing. This review gives an overview of the current knowledge on TGF-β signaling and the intracellular TGF-β signaling pathway in fetal fibroblasts. Furthermore, this review also describes the various components that regulate the cellular TGF-β response and hypothesizes about the possible roles these components might play in the altered response of fetal fibroblasts to TGF-β.

Angiotensin II regulates collagen metabolism through modulating tissue inhibitor of metalloproteinase-1 in diabetic skin tissues

We investigated the effect of angiotensin II (Ang II) on matrix metalloproteinase-1 (MMP-1)/tissue inhibitor of metalloproteinase-1 (TIMP-1) balance in regulating collagen metabolism of diabetic skin. Skin tissues from diabetic model were collected, and the primary cultured fibroblasts were treated with Ang II receptor inhibitors before Ang II treatment. The collagen type I (Coll I) and collagen type III (Coll III) were measured by histochemistry. The expressions of transforming growth factor-β (TGF-β), MMP-1, TIMP-1 and propeptides of types I and III procollagens in skin tissues and fibroblasts were quantified using polymerase chain reaction (PCR), Western blot or enzyme-linked immunosorbent assay (ELISA). Collagen dysfunction was documented by changed collagen I/III ratio in streptozotocin (STZ)-injected mice compared with controls. This was accompanied by increased expression of TGF-β, TIMP-1 and propeptides of types I and III procollagens in diabetic skin tissues. In primary cultured fibroblasts, Ang II prompted collagen synthesis accompanied by increases in the expressions of TGF-β, TIMP-1 and types I and III procollagens, and these increases were inhibited by losartan, an Ang II type 1 (AT1) receptor blocker, but not affected by PD123319, an Ang II type 2 (AT2) receptor antagonist. These findings present evidence that Ang-II-mediated changes in the productions of MMP-1 and TIMP-1 occur via AT1 receptors and a TGF-β-dependent mechanism.

The role of gene therapy in regenerative surgery: updated insights

BACKGROUND

In the past two decades, regenerative surgeons have focused increasing attention on the potential of gene therapy for treatment of local disorders and injuries. Gene transfer techniques may provide an effective local and short-term induction of growth factors without the limits of other topical therapies. In 2002, Tepper and Mehrara accurately reviewed the topic: given the substantial advancement of research on this issue, an updated review is provided.

METHODS

Literature indexed in the National Center for Biotechnology Information database (PubMed) has been reviewed using variable combinations of keywords ("gene therapy," "regenerative medicine," "tissue regeneration," and "gene medicine"). Articles investigating the association between gene therapies and local pathologic conditions have been considered. Attention has been focused on articles published after 2002. Further literature has been obtained by analysis of references listed in reviewed articles.

RESULTS

Gene therapy approaches have been successfully adopted in preclinical models for treatment of a large variety of local diseases affecting almost every type of tissue. Experiences in abnormalities involving skin (e.g., chronic wounds, burn injuries, pathologic scars), bone, cartilage, endothelia, and nerves have been reviewed. In addition, the supporting role of gene therapies to other tissue-engineering approaches has been discussed. Despite initial reports, clinical evidence has been provided only for treatment of diabetic ulcers, rheumatoid arthritis, and osteoarthritis.

CONCLUSIONS

Translation of gene therapy strategies into human clinical trials is still a lengthy, difficult, and expensive process. Even so, cutting-edge gene therapy-based strategies in reconstructive procedures could soon set valuable milestones for development of efficient treatments in a growing number of local diseases and injuries.

Complements and the wound healing cascade: an updated review

Wound healing is a complex pathway of regulated reactions and cellular infiltrates. The mechanisms at play have been thoroughly studied but there is much still to learn. The health care system in the USA alone spends on average 9 billion dollars annually on treating of wounds. To help reduce patient morbidity and mortality related to abnormal or prolonged skin healing, an updated review and understanding of wound healing is essential. Recent works have helped shape the multistep process in wound healing and introduced various growth factors that can augment this process. The complement cascade has been shown to have a role in inflammation and has only recently been shown to augment wound healing. In this review, we have outlined the biology of wound healing and discussed the use of growth factors and the role of complements in this intricate pathway.

Dynamics of Transforming Growth Factor Beta Signaling in Wound Healing and Scarring

SIGNIFICANCE

Wound healing is an intricate biological process in which the skin, or any other tissue, repairs itself after injury. Normal wound healing relies on the appropriate levels of cytokines and growth factors to ensure that cellular responses are mediated in a coordinated manner. Among the many growth factors studied in the context of wound healing, transforming growth factor beta (TGF-β) is thought to have the broadest spectrum of effects.

RECENT ADVANCES

Many of the molecular mechanisms underlying the TGF-β/Smad signaling pathway have been elucidated, and the role of TGF-β in wound healing has been well characterized. Targeting the TGF-β signaling pathway using therapeutic agents to improve wound healing and/or reduce scarring has been successful in pre-clinical studies.

CRITICAL ISSUES

Although TGF-β isoforms (β1, β2, β3) signal through the same cell surface receptors, they display distinct functions during wound healing in vivo through mechanisms that have not been fully elucidated. The challenge of translating preclinical studies targeting the TGF-β signaling pathway to a clinical setting may require more extensive preclinical research using animal models that more closely mimic wound healing and scarring in humans, and taking into account the spatial, temporal, and cell-type-specific aspects of TGF-β isoform expression and function.

FUTURE DIRECTIONS

Understanding the differences in TGF-β isoform signaling at the molecular level and identification of novel components of the TGF-β signaling pathway that critically regulate wound healing may lead to the discovery of potential therapeutic targets for treatment of impaired wound healing and pathological scarring.

Effect of transforming growth factor Beta 1 on wound healing in induced diabetic rats

OBJECTIVE

Delayed wound healing is one of the complications of diabetes mellitus, exhibited by profound inflammation and decreased granulation tissues. The current study was carried out to evaluate wound healing in both normal and diabetic rats. In addition, it evaluated the potential protective effect of transforming growth factor β1 (TGF β1), that has the broadest spectrum of actions, affecting all cell types that are involved in all stages of wound healing to accelerate wound healing in normal & diabetic rats.

METHODS

: The present study was performed on 40 male albino rats. Each 10 rats were designed as a group. Group I saved as control. They received incisional wound in their tongues 1 cm length and 1/2 cm depth. Group II received 500 ng/kg of TGF β1 5 minutes before wounding. Group III diabetes was induced then rats were treated as second group. At the 14(th) day post wounding, sections of tongues were taken for hematoxylin and eosin and Masson's trichome staining to examine the histological changes. The intracellular actions of TGF β1 were studied by TEM.

RESULTS

A higher cell proliferation rate and a denser and more organized new extracellular matrix and complete wound closure was detected at the 14(th) days in the TGF β1 treated wound in comparison with the 14(th) days for the untreated, control groups. There were delayed wound healing in diabetic rats, decreased re-epithelialization, granulation tissue thickness, matrix density, number of infiltrated cells, and number of capillaries. In TGF β1 treated diabetic rats, showed significant healing improvement was obvious as compared with diabetic rats.

CONCLUSIONS

A single intravenous injection of TGF β1 was sufficient to enhance wound healing in rat's tongue. This approach represents a new strategy that may be applied to the treatment of incisional wounds in human diabetic patients.

Wound modulation after filtration surgery

Filtration surgery is the standard invasive procedure for the management of intraocular pressure in advanced glaucoma. The key to a successful outcome is to modulate the normal wound healing cascade that leads to closure of the newly created aqueous outflow pathway. Antifibrotic agents such as mitomycin C and 5-fluorouracil have been increasingly used to modulate the wound healing process and increase surgical success. Although these agents have proven efficacy, they also increase the risk of complications. Efforts have centered on the identification of novel agents and techniques that can influence wound modulation without these complications. We detail new agents and methods under investigation to control wound healing after filtration surgery.

Wound healing after radiation therapy: review of the literature

Radiation therapy is an established modality in the treatment of head and neck cancer patients. Compromised wound healing in irradiated tissues is a common and challenging clinical problem. The pathophysiology and underlying cellular mechanisms including the complex interaction of cytokines and growth factors are still not understood completely. In this review, the current state of research regarding the pathomechanisms of compromised wound healing in irradiated tissues is presented. Current and possible future treatment strategies are critically reviewed.

Rosiglitazone attenuates activation of human Tenon's fibroblasts induced by transforming growth factor-β1

PURPOSE

To investigate the influence of rosiglitazone on activation of human Tenon's fibroblasts (HTFs) and to access the possible mechanism.

METHODS

Cultured human Tenon's fibroblasts were pretreated in two different concentrations of rosiglitazone (5 μmol/l and 10 μmol/l) before being stimulated with 5 ng/ml transforming growth factor β1 (TGF-β1). The viability and proliferation of cells were accessed by cell count kit-8 assay; Cell migration was examined by the wound closure assay; Alpha smooth muscle actin (α-SMA), connective tissue growth factor (CTGF) and type I collagen (COL I) transcription were detected by RT-qPCR; The expression and localization of α-SMA protein were examined by Western-blot analysis and Immunofluorescence staining; Western-blot analysis was also used to check the expression of CTGF, COL I peroxisome proliferator-activated receptor gamma (PPAR-γ), and phosphorylation of the signaling protein Smad2/3

RESULTS

Rosiglitazone is able to attenuate the up-regulation of α-SMA, CTGF, and COL I transcription, as well as affect protein expression, proliferation, and migration of cells; rosiglitazone also can increase PPAR-γ expression and attenuate Smad2/3 phosphorylation.

CONCLUSIONS

Rosiglitazone can effectively attenuate activation of HTFs induced by TGF-β1 without obvious toxicity. The possible mechanism might be that rosiglitazone interferes with TGF-β/Smad signaling pathway.

Nano-vectors for the Ocular Delivery of Nucleic Acid-based Therapeutics

Nucleic acid-based therapeutics have gained a lot of interest for the treatment of diverse ophthalmic pathologies. The first to enter in clinic has been an oligonucleotide, Vitravene^® for the treatment of cytomegalovirus infection. More recently, research on aptamers for the treatment of age related macular degeneration has led to the development of Macugen^®. Despite intense potential, effective ocular delivery of nucleic acids is a major challenge since therapeutic targets for nucleic acid-based drugs are mainly located in the posterior eye segment, requiring repeated invasive administration. Of late, nanotechnology-based nano-vectors have been developed in order to overcome the drawbacks of viral and other non-viral vectors. The diversity of nano-vectors allows for ease of use, flexibility in application, low-cost of production, higher transfection efficiency and enhanced genomic safety. Using nano-vector strategies, nucleic acids can be delivered either encapsulated or complexed with cationic lipids, polymers or peptides forming sustained release systems, which can be tailored according to the ocular tissue being targeted. The present review focuses on developments and advances in various nano-vectors for the ocular delivery of nucleic acid-based therapeutics, the barriers that such delivery systems face and methods to overcome them.

Ion-activated in situ gelling systems for antisense oligodeoxynucleotide delivery to the ocular surface

Ion-activated in situ gelling systems are able to cross-link with the cations present in the tear fluid, forming a gel on the ocular surface and prolonging corneal contact time. Corneal scrape wounding offers an exceptional model to investigate the efficacy of these formulations for connexin43 (Cx43) antisense oligodeoxynucleotide (AsODN) delivery used to improve wound repair. Systems based on gellan gum and carrageenan have previously been found advantageous in terms of their physicochemical properties, in vitro and in vivo release profiles and precorneal retention. The present study describes AsODN penetration into corneal tissue after wounding and determines the formulations' delivery efficacy by evaluating wound size, tissue inflammation and connexin levels. No difference was shown between the penetration patterns of the formulations, with most of the AsODN accumulating in the epithelium close to the wound leading edge and the stroma underlying the wound. However, significant differences were seen in the delivery efficacy, with gellan gum and carrageenan based systems resulting in the lowest connexin levels and subsequently in the greatest reduction in wound size, the least stromal edema and hypercellularity. This demonstrates their potential use as delivery vehicles for AsODNs to the ocular surface.

The role of different VEGF isoforms in scar formation after glaucoma filtration surgery

Vascular endothelial growth factor (VEGF) plays an important role in both physiological and pathological angiogenesis. Our previous studies showed a differential role of VEGF isoforms in retinal physiological angiogenesis. We also demonstrated that non-selective inhibition of VEGF by bevacizumab had a beneficial effect on surgical outcome after glaucoma filtration surgery by reducing angiogenesis as well as fibrosis. However, the function of the VEGF isoforms in pathological angiogenesis and wound healing in the eye still remains unidentified. This study was designed to elucidate the differential roles of VEGF isoforms in scar formation after trabeculectomy. Furthermore, we also investigated whether pegaptanib (Macugen™, Pfizer), an aptamer which specifically blocks VEGF(165), could improve surgical outcome by reducing postoperative scarring. VEGF-R2 and neuropilin-1 (NRP-1) expression was analyzed in vitro by RT-PCR, and were found to be expressed at higher levels in human umbilical vein endothelial cells (HUVEC) as compared to Tenon fibroblasts (TF). The effect of the different VEGF isoforms (VEGF(121), VEGF(165) and VEGF(189)) and pegaptanib on cell proliferation was determined via WST-1 assay. Endothelial cell proliferation was stimulated after addition of VEGF(121) and VEGF(165), whereas VEGF(121) and VEGF(189) increased fibroblast growth. These effects on proliferation were associated with an activation of the ERK pathway, as revealed using the TransAM c-Myc assay. Inhibition of the ERK pathway, by PD98059 administration, significantly reduced VEGF isoform induced cell growth. A dose-dependent reduction of endothelial cell proliferation was observed after pegaptanib administration, while only the highest dose was able to inhibit fibroblast growth. Next, the in vivo effect of pegaptanib was investigated in a rabbit model of trabeculectomy. The surgical outcome was evaluated by performing clinical investigations (IOP, bleb area, height and survival), as well as histomorphometric analyses of angiogenesis (CD31), inflammation (CD45) and fibrosis (Sirius Red). A single postoperative application of pegaptanib had a beneficial impact on surgical outcome, mainly by reducing angiogenesis, but not inflammation or collagen deposition. Repeated injections slightly improved surgical outcome, but again solely by reducing angiogenesis. In summary, our results revealed that the VEGF isoforms play a differential role in ocular wound healing: VEGF(165) and VEGF(121) predominantly affect blood vessel growth, whereas VEGF(189) is rather involved in fibrosis, an important process in wound healing.

RNA interference of transforming growth factor-β 2 in human respiratory fibroblasts

OBJECTIVE

Transforming growth factor-β2 (TGF-β2) is a principal cytokine of interest in the pathogenesis of scar formation and is a potential target for future molecular-based adjunctive therapies. The authors hypothesize that interfering RNA (RNAi) can be used to modulate TGF-β2 production in cultured human respiratory fibroblasts.

STUDY DESIGN

Basic science. Setting. Laboratory.

SUBJECTS AND METHODS

RNAi constructs targeted to the TGF-β2 transcript were complexed with microsomal lipids and applied to human fibroblasts in cell culture. Transfection efficiency and cell viability were measured by fluorescence microscopy. Messenger RNA (mRNA) for TGF-β2 was measured 48 hours posttransfection using real-time quantitative PCR. The quantity of TGF-β2 protein produced with increasing concentrations of RNAi was measured using enzyme-linked immunosorbent assay. The function of RNAi-treated fibroblasts was tested using a wound-healing assay.

RESULTS

Transfection efficiency of more than 80% was achieved with minimal induced cell death. Treated cells showed selective knockdown of 80% of TGF-β2 mRNA, which was confirmed with negative controls. As the concentration of RNAi was increased, an incremental decrease in TGF-β2 protein was measured.

CONCLUSION

RNAi technology is an effective means of localized and transient gene silencing in cultured human fibroblasts. Transfection can be achieved using microsome complexed RNAi with minimal induced cell death. This preliminary result shows promise for future in vitro studies.

TGFB1-induced extracellular expression of TGFBIp and inhibition of TGFBIp expression by RNA interference in a human corneal epithelial cell line

PURPOSE

To report the increased production of extracellular transforming growth factor β-induced protein (TGFBIp) by human corneal epithelial cells (HCECs) after induction by TGFB1 and the inhibition of TGFBIp production in induced and noninduced HCECs by RNA interference (RNAi).

METHODS

HCECs were cultured in serum-free medium and treated with 0 or 10 ng/mL TGFB1 over a period of 72 hours. Commercially available siRNAs targeting TGFBI mRNA were mixed with a transfection reagent and used to reverse transfect TGFB1-induced and noninduced HCECs. Extracellular and intracellular concentrations of TGFBIp were measured by ELISA and Western blot analysis, respectively, and TGFBI RNA was assayed using semiquantitative RT-PCR.

RESULTS

HCECs constitutively express TGFBIp, and treatment with TGFB1 results in up to a fourfold increase in the amount of extracellular TGFBIp. Four commercially available siRNAs targeting TGFBI mRNA produced a >70% decrease in extracellular TGFBIp within 48 hours after transfection of noninduced HCECs but a <25% decrease in extracellular TGFBIp by 48 hours after transfection of TGFB1-induced HCECs. The suppression of extracellular TGFBIp production correlated with a decrease in intracellular TGFBIp production and TGFBI mRNA expression after transfection.

CONCLUSIONS

Extracellular TGFBIp expression by HCECs is increased several fold after exposure to TGFB1. Both HCEC-constitutive and HCEC-induced TGFBIp production can be inhibited with RNA interference, though the effect was greater and lasted longer for constitutive than induced TGFBIp production. Given that the corneal deposits in the TGFBI dystrophies consist of TGFBIp derived from HCECs, RNAi represents a potential means to inhibit primary dystrophic deposit formation and recurrence after surgical intervention.

Hypertrophic scarring and keloids: pathomechanisms and current and emerging treatment strategies

Excessive scars form as a result of aberrations of physiologic wound healing and may arise following any insult to the deep dermis. By causing pain, pruritus and contractures, excessive scarring significantly affects the patient's quality of life, both physically and psychologically. Multiple studies on hypertrophic scar and keloid formation have been conducted for decades and have led to a plethora of therapeutic strategies to prevent or attenuate excessive scar formation. However, most therapeutic approaches remain clinically unsatisfactory, most likely owing to poor understanding of the complex mechanisms underlying the processes of scarring and wound contraction. In this review we summarize the current understanding of the pathophysiology underlying keloid and hypertrophic scar formation and discuss established treatments and novel therapeutic strategies.

Dual interference with novel genes mfgl2 and mTNFR1 ameliorates murine hepatitis virus type 3-induced fulminant hepatitis in BALB/cJ mice

Our studies and those of many others have implicated hepatocyte necrosis and apoptosis mediated by fibrinogen-like protein-2 (fgl2) prothrombinase and tumor necrosis factor receptor (TNFR) in the development of fulminant viral hepatitis, a disease with a mortality rate greater than 80% in cases lacking immediate organ transplantation. This study was designed to explore the efficacy of dual short hairpin RNA (shRNA) interference with fgl2 and TNFR1 in the treatment of murine hepatitis virus strain 3 (MHV-3)-induced fulminant hepatitis in mice. Plasmids p-mfgl2shRNA and p-mTNFR1shRNA, complementary to the sequences for mfgl2 and mTNFR1, were constructed. Plasmids pEGFP-mfgl2 and pEGFP-mTNFR1 expressing mfgl2-EGFP (enhanced green fluorescent protein) and mTNFR1-EGFP fusion proteins were also constructed to screen the inhibitory effect of p-mfgl2shRNA and p-mTNFR1shRNA on mfgl2 and mTNFR1 expression. Cotransfection of individual shRNA plasmids and pcDNA3.0-mfgl2 and pcDNA3.0-mTNFR1 expression constructs into Chinese hamster ovary (CHO) cells significantly inhibited mfgl2 and mTNFR1 gene expression, as evidenced by fluorescence microscopy, reverse transcription-polymerase chain reaction, and Western blotting. In vivo hydrodynamic delivery of dual-interference shRNA plasmids for mfgl2 and mTNFR1 significantly decreased mfgl2 and mTNFR1 expression; markedly ameliorated fibrin deposition, hepatocyte necrosis, and apoptosis; and prolonged survival against fulminant viral hepatitis induced by MHV-3 in BALB/cJ mice compared with mfgl2 or TNFR1 single-gene interference. These results indicate that in vivo interference with genes for more than one key target provides superior treatment efficacy compared with single-gene interference.

Potential therapeutic targets for cardiac fibrosis: TGFbeta, angiotensin, endothelin, CCN2, and PDGF, partners in fibroblast activation

Fibrosis is one of the largest groups of diseases for which there is no therapy but is believed to occur because of a persistent tissue repair program. During connective tissue repair, "activated" fibroblasts migrate into the wound area, where they synthesize and remodel newly created extracellular matrix. The specialized type of fibroblast responsible for this action is the alpha-smooth muscle actin (alpha-SMA)-expressing myofibroblast. Abnormal persistence of the myofibroblast is a hallmark of fibrotic diseases. Proteins such as transforming growth factor (TGF)beta, endothelin-1, angiotensin II (Ang II), connective tissue growth factor (CCN2/CTGF), and platelet-derived growth factor (PDGF) appear to act in a network that contributes to myofibroblast differentiation and persistence. Drugs targeting these proteins are currently under consideration as antifibrotic treatments. This review summarizes recent observations concerning the contribution of TGFbeta, endothelin-1, Ang II, CCN2, and PDGF and to fibroblast activation in tissue repair and fibrosis and the potential utility of agents blocking these proteins in affecting the outcome of cardiac fibrosis.

Role of transforming growth factor-β in airway remodeling in asthma

TGF-β is one of the main mediators involved in tissue remodeling in the asthmatic lung. This profibrotic cytokine is produced by a number of cells, including macrophages, epithelial cells, fibroblasts, and eosinophils. High expression of TGF-β in patients with asthma was reported by many investigators. However, controversy remains whether the concentration of TGF-β correlates with disease severity. TGF-β is believed to play an important role in most of the cellular biological processes leading to airway remodeling. It was shown to be involved in epithelial changes, subepithelial fibrosis, airway smooth muscle remodeling, and microvascular changes. Here, sources of TGF-β, as well as its role in the development of airway remodeling, will be reviewed. Therapeutic strategies that modulate TGF-β will also be discussed.

Inhibitory effect of antisense oligonucleotide targeting TIMP-2 on immune-induced liver fibrosis

INTRODUCTION

We previously reported that both experimental and human studies have shown the importance of TIMP-1 and TIMP-2 in the development of liver fibrosis, a disease mostly caused by HBV and HCV infection in China. Inhibiting the expression of TIMP-1 by an antisense oligonucleotide (ASON) can prevent liver fibrosis through decreasing the deposition of collagen I and III. Whether blocking the expression of TIMP-2 has the same effect on liver fibrosis is not clear.

MATERIALS AND METHODS

To interfere with this potentially effective target, we designed and synthesized two different ASON targeting TIMP-2, then mixed and transfected them by hydrodynamic injection into the rat livers with immune-induced liver fibrosis. We isolated HSCs from the HSA-induced rat model with liver fibrosis, and transfected them with ASON or sense oligonucleotide in vitro.

RESULTS

We observed that TIMP-2 ASON markedly reduced the expression of TIMP-2 by real-time PCR, Western blot, and enzyme linked immunosorbent assay. However, TIMP-2 ASON had little effect on alpha-SMA expression in vitro by Western blot. Inhibition of the expression of TIMP-2 by TIMP-2 ASON clearly decreased deposition of collagen I and IV, ameliorated liver pathology, and improved the liver function among the rats with immune-induced liver fibrosis.

CONCLUSION

The results suggested that TIMP-2 ASON could prevent the progression of liver fibrosis in this rat model. It is possible that this could form the basis for exploration of new liver anti-fibrosis drugs at a genetic level.

Chitosan-based nanostructures: a delivery platform for ocular therapeutics

Nanoscience and nanotechnology has caused important breakthroughs in different therapeutic areas. In particular, the application of nanotechnology in ophthalmology has led to the development of novel strategies for the treatment of ocular disorders. Indeed, the association of an active molecule to a nanocarrier allows the molecule to intimately interact with specific ocular structures, to overcome ocular barriers and to prolong its residence in the target tissue. Over the last decade, our group has designed and developed a delivery platform based on the polysaccharide chitosan, which suits the requirements of the topical ocular route. These nanosystems have been specifically adapted for the delivery of hydrophilic and lipophilic drugs and also polynucleotides onto the eye surface. The results collected up until now suggest the potential of this delivery platform and the subsequent need of a full preclinical evaluation in order to satisfy the specific regulatory demands of this mode of administration.

Immunohistochemical Localization of EGF, TGF-α, TGF-β, and Their Receptors in Rat Corneas During Healing of Excimer Laser Ablation

PURPOSE

Members of the epidermal growth factor (EGF) and transforming growth factor beta (TGF-beta) families of growth factors and receptors are known to regulate key aspects of corneal wound healing, including epithelial migration and scar formation. To further understand their roles, mRNA levels were measured and proteins were immunolocalized in rat corneas at multiple time points during healing of excimer laser ablation injury.

METHODS

Excimer laser photoablation was performed to a depth of 50 microm on rat corneas. Levels of mRNAs for EGF, TGF-alpha, TGF-beta isoforms 1, 2, and 3, and their receptors (EGF-R and TGFbeta-IIR) were measured by quantitative RT-PCR on days 0, 1.5, 7, 21, 42, and 91 after ablation. Immunohistochemical localization of the growth factors and their receptors was performed on days 0, 7, and 21 in corneal sections.

RESULTS

Levels of EGF mRNA remained stable in rat corneas after ablation (68 +/- 12 copies/cell, mean +/- SD), whereas levels of TGF-alpha mRNA progressively increased sixfold to a maximum at day 42 (300 copies/cell) then slightly decreased on day 91. Levels of EGF-R mRNA rapidly increased 60-fold on day 7 compared with day 0 (571 vs. 9 copies/cell) then decreased sixfold above baseline at day 91. Levels of TGF-beta1 mRNA remained stable (36 +/- 10 copies/cell), whereas levels of TGF-beta2 and TGF-beta3 mRNAs peaked on day 21 (300-fold and 25-fold increase) and remained elevated through day 91. Levels of TGFbeta-IIR mRNA showed a similar pattern. Immunostaining of all the growth factors and receptors was primarily in basal layers of epithelial cells in uninjured cornea and during healing. Intensity of immunostaining for TGF-beta1, TGFbeta-IR, and TGFbeta-IIR increased appreciably in the basal epithelial layers after ablation.

CONCLUSIONS

Levels of mRNAs for several key members of the EGF and TGF-beta systems increase during corneal wound healing. In addition, the proteins are primarily localized in basal layers of epithelial cells, which suggest these cells are active in synthesizing autocrine and paracrine growth factors that modulate corneal wound healing.

Trichostatin a inhibits corneal haze in vitro and in vivo

PURPOSE

Trichostatin A (TSA), a histone deacetylase inhibitor, has been shown to suppress TGF-beta-induced fibrogenesis in many nonocular tissues. The authors evaluated TSA cytotoxicity and its antifibrogenic activity on TGF-beta-driven fibrosis in the cornea with the use of in vitro and in vivo models.

METHODS

Human corneal fibroblasts (HSFs) were used for in vitro studies, and New Zealand White rabbits were used for in vivo studies. Haze in the rabbit cornea was produced with photorefractive keratectomy (PRK) using excimer laser. Trypan blue exclusion and MTT assays evaluated TSA cytotoxicity to the cornea. Density of haze in the rabbit eye was graded with slit lamp biomicroscopy. Real-time PCR, immunoblotting, or immunocytochemistry was used to measure alpha-smooth muscle actin (SMA), fibronectin, and collagen type IV mRNA or protein levels. TUNEL assay was used to detect cell death.

RESULTS

TSA concentrations of 250 nM or less were noncytotoxic and did not alter normal HSF morphology or proliferation. TGF-beta1 treatment of HSF significantly increased mRNA and protein levels of SMA (9-fold), fibronectin (2.5-fold), and collagen type IV (2-fold). TSA treatment showed 60% to 75% decreases in TGF-beta1-induced SMA and fibronectin mRNA levels and 1.5- to 3.0-fold decreases in protein levels but had no effect on collagen type IV mRNA or protein levels in vitro. Two-minute topical treatment of TSA on rabbit corneas subjected to -9 D PRK significantly decreased corneal haze in vivo.

CONCLUSIONS

TSA inhibits TGF-beta1-induced accumulation of extracellular matrix and myofibroblast formation in the human cornea in vitro and markedly decreases haze in rabbit cornea in vivo.

Transforming growth factor-beta signaling: emerging stem cell target in metastatic breast cancer?

In most human breast cancers, lowering of TGFbeta receptor- or Smad gene expression combined with increased levels of TGFbetas in the tumor microenvironment is sufficient to abrogate TGFbetas tumor suppressive effects and to induce a mesenchymal, motile and invasive phenotype. In genetic mouse models, TGFbeta signaling suppresses de novo mammary cancer formation but promotes metastasis of tumors that have broken through TGFbeta tumor suppression. In mouse models of "triple-negative" or basal-like breast cancer, treatment with TGFbeta neutralizing antibodies or receptor kinase inhibitors strongly inhibits development of lung- and bone metastases. These TGFbeta antagonists do not significantly affect tumor cell proliferation or apoptosis. Rather, they de-repress anti-tumor immunity, inhibit angiogenesis and reverse the mesenchymal, motile, invasive phenotype characteristic of basal-like and HER2-positive breast cancer cells. Patterns of TGFbeta target genes upregulation in human breast cancers suggest that TGFbeta may drive tumor progression in estrogen-independent cancer, while it mediates a suppressive host cell response in estrogen-dependent luminal cancers. In addition, TGFbeta appears to play a key role in maintaining the mammary epithelial (cancer) stem cell pool, in part by inducing a mesenchymal phenotype, while differentiated, estrogen receptor-positive, luminal cells are unresponsive to TGFbeta because the TGFBR2 receptor gene is transcriptionally silent. These same cells respond to estrogen by downregulating TGFbeta, while antiestrogens act by upregulating TGFbeta. This model predicts that inhibiting TGFbeta signaling should drive the differentiation of mammary stem cells into ductal cells. Consequently, TGFbeta antagonists may convert basal-like or HER2-positive cancers to a more epithelioid, non-proliferating (and, perhaps, non-metastatic) phenotype. Conversely, these agents might antagonize the therapeutic effects of anti-estrogens in estrogen-dependent luminal cancers. These predictions need to be addressed prospectively in clinical trials and should inform the selection of patient populations most likely to benefit from this novel anti-metastatic therapeutic approach.

Transforming growth factor-beta in allergic inflammatory disease of the upper airways: friend or foe?

TGF-beta is a multi-functional cytokine with a huge array of effects on a variety of cell types. It is rapidly emerging as a key major player in the way the airway epithelium behaves and its ability to repair itself. This is not only of relevance to allergic airway diseases such as asthma and allergic rhinitis, which are increasing in prevalence worldwide, but in many other diseases. The full impact any disruption of TGF-beta signalling may have in the development and persistence of allergic inflammatory airway diseases is yet to be fully realized and remains the subject of ongoing research. There has been a recent revival of interest in the role of regulatory T cells in controlling allergic inflammation. Evidence is emerging of a significant contribution by TGF-beta to this regulatory process. This review aims to summarize current knowledge relating to TGF-beta in relation to allergic inflammatory upper airways disease, and attempts to clarify some of the discrepancies and inconsistencies in this area. It also considers the therapeutic implications of novel TGF-beta therapy, including potential future applications in the treatment of nasal polyposis and reduction of post-operative scar tissue formation following endoscopic sinus surgery.

Antisense targeting of cFLIP sensitizes activated T cells to undergo apoptosis and desensitizes responses to contact dermatitis

Contact dermatitis is the result of inflammatory responses mediated by hapten-specific activated CD8+ and CD4+ T cells. Activation-induced cell death (AICD) is a naturally occurring process regulating the resolution of T-cell responses through decreased expression of the antiapoptotic molecule cellular FLICE inhibitory protein (cFLIP). We show that targeting cFLIP expression in vitro and in vivo, with morpholino antisense applied systemically or topically in conjunction with antigen, sensitizes T cells to undergo "early" AICD resulting in tolerance. Analysis of antisense-treated CD8+ OT-1 splenocytes after co-culture with SIINFEKL-pulsed DCs showed apoptosis occurring in a dose-dependent manner with respect to cFLIP peptide-conjugated phosphorodiamidate morpholino oligomer (PPMO) concentration. A transplant acceptance model using male DO.11 donor cells and female BALB/c recipient mice showed that cFLIP antisense treatment could promote antigen tolerance. Hypersensitivity responses induced in mice by the epicutaneous application of the haptens FITC and oxazolone confirmed that topically applied cFLIP antisense could reduce inflammation. Treatment of the skin produced significant reduction in dermatitis and localized infiltration of lymphocytes. Moreover, the treatment was target- and antigen-specific, dose-dependent, and capable of inducing long-lived tolerance. These data suggest that the targeted expression of immune-regulating molecules is possible through the application of antisense to the skin.

Antisense makes sense in engineered regenerative medicine

The use of antisense strategies such as ribozymes, oligodeoxynucleotides (ODNs) and small interfering RNA (siRNA) in gene therapy, in conjunction with the use of stem cells and tissue engineering, has opened up possibilities in curing degenerative diseases and injuries to non-regenerating organs and tissues. With their unique ability to down-regulate or silence gene expression, antisense oligonucleotides are uniquely suited in turning down the production of pathogenic or undesirable proteins and cytokines. Here, we review the antisense strategies and their applications in regenerative medicine with a focus on their efficacies in promoting cell viability, regulating cell functionalities as well as shaping an optimal microenvironment for therapeutic purposes.

Prevention and management of hypertrophic scars and keloids after burns in children

Hypertrophic scars and keloids are challenging to manage, particularly as sequelae of burns in children in whom the psychologic burden and skin characteristics differ substantially from adults. Prevention of hypertrophic scars and keloids after burns is currently the best strategy in their management to avoid permanent functional and aesthetical alterations. Several actions can be taken to prevent their occurrence, including parental and children education regarding handling sources of fire and flammable materials, among others. Combination of therapies is the mainstay of current burn scar management, including surgical reconstruction, pressure therapy, silicon gels and sheets, and temporary garments. Other adjuvant therapies such as topical imiquimod, tacrolimus, and retinoids, as well as intralesional corticosteroids, 5-fluorouracil, interferons, and bleomycin, have been used with relative success. Cryosurgery and lasers have also been reported as alternatives. Newer treatments aimed at molecular targets such as cytokines, growth factors, and gene therapy, currently in developing stages, are considered the future of the treatment of postburn hypertrophic scars and keloids in children.

Scars: a review of emerging and currently available therapies

BACKGROUND

With the investigation and potential introduction of several novel scar-reducing therapies to the market within the next several years, it is germane to review both the pathophysiology of scarring and the safety and efficacy of currently available and emerging therapeutic agents.

METHODS

An extensive review of the English-language literature was conducted using the MEDLINE database.

RESULTS

A comprehensive review of the pathophysiology of scarring and scar management, including both emerging and currently available therapies, was completed. Current clinical studies are limited by small sample sizes, lack of well-designed controls, and lack of standardized scar outcome measurement parameters.

CONCLUSIONS

A prominent challenge in the study of scar management is the paucity of well-designed, large, randomized, controlled studies examining existing scar-reducing techniques. The greatest improvement in scar-reducing protocols likely entails a polytherapeutic strategy for management. Further investigation into the role of inflammation in scarring is paramount to the development of improved scar-reducing agents. There is a need for large controlled trials using a polytherapeutic strategy that combines existing and novel agents to provide a standardized evidence-based evaluation of efficacy.

Recent perspectives in ocular drug delivery

Anatomy and physiology of the eye makes it a highly protected organ. Designing an effective therapy for ocular diseases, especially for the posterior segment, has been considered as a formidable task. Limitations of topical and intravitreal route of administration have challenged scientists to find alternative mode of administration like periocular routes. Transporter targeted drug delivery has generated a great deal of interest in the field because of its potential to overcome many barriers associated with current therapy. Application of nanotechnology has been very promising in the treatment of a gamut of diseases. In this review, we have briefly discussed several ocular drug delivery systems such as microemulsions, nanosuspensions, nanoparticles, liposomes, niosomes, dendrimers, implants, and hydrogels. Potential for ocular gene therapy has also been described in this article. In near future, a great deal of attention will be paid to develop non-invasive sustained drug release for both anterior and posterior segment eye disorders. A better understanding of nature of ocular diseases, barriers and factors affecting in vivo performance, would greatly drive the development of new delivery systems. Current momentum in the invention of new drug delivery systems hold a promise towards much improved therapies for the treatment of vision threatening disorders.

Connective tissue growth factor modulates extracellular matrix production in human subconjunctival fibroblasts and their proliferation and migration in vitro

PURPOSE

We examined the role of connective tissue growth factor (CTGF) in transforming growth factor beta1 (TGFbeta1)-related behavior in cultured human subconjunctival fibroblasts (SCFs), protein production, mRNA expression of CTGF and type I collagen alpha1 chain (colIA1), and cell proliferation and migration. TGFbeta1 is the major factor involved in bleb scarring following filtration surgery.

METHODS

An antisense deoxynucleotide (antisense) (5 microM) for CTGF mRNA was used to block endogenous CTGF expression. Effects of antisense on extracellular matrix (ECM) production and immunolocalization, mRNA expression, and cell proliferation and migration were examined in human SCF cultures with or without TGFbeta1 (5 ng/ml). Cell migration was examined in an in vitro wound model of monolayer fibroblast cultures.

RESULTS

CTGF antisense reduced mRNA expression of CTGF and colIA1 and production of the ECM components type I collagen, and fibronectin much more markedly in cells treated with TGFbeta1 compared with control fibroblasts, and it inhibited the proliferation of cultured SCFs to 71.9% of that of controls after 13 days of culture. CTGF antisense also delayed defect closure in monolayer cell sheets. In the culture, the defect was closed by TGFbeta1 by 36 h, whereas 7.0% of the defect remained at 48 h in the antisense-treated culture.

CONCLUSIONS

These findings indicate that CTGF is involved in ECM production in SCFs activated by exogenous TGFbeta1 in vitro. Inhibition of CTGF expression may be effective in preventing undesirable scar formation during healing following filtration surgery.

Modulation of wound healing during and after glaucoma surgery

Following all types of glaucoma filtration surgery (GFS), scarring still poses the major threat to long-term success. The healing and scarring determine the percentage of patients achieving low final intraocular pressures (IOPs) that are associated with virtually no glaucoma progression. The use of antifibrotic agents to inhibit scarring of trabeculectomy blebs is now a well-established clinical practice. Unfortunately, severe complications such as leakage, infection, hypotony, and endophthalmitis with complete loss of vision may occur. In addition, surgery still fails in some individuals despite maximal doses of current antifibrotics. Better therapeutic agents are needed. Many promising new agents are being evaluated clinically and in vitro. In this chapter, we will discuss our current understanding of the wound healing process after glaucoma surgery and promising new treatment modalities.

Basics of TGF-beta and pancreatic cancer

Pancreatic cancer is the 4th leading cause of cancer-related death in the United States. The number of diagnoses per year equals the number of deaths per year, making it the deadliest of all malignancies. Modern advances and breakthroughs in molecular oncology have allowed researchers to gain a better understanding of the mechanisms responsible for the pathogenesis of this disease. The transforming growth factor-beta (TGF-beta) pathway is one of the signaling systems that has been identified as a major contributor. TGF-beta plays a paradoxical role as both a tumor suppressor and a tumor promoter in pancreatic cancer. The purpose of this review is to provide the practicing clinician a thorough review of this molecule and its associated signaling partners in the context of its duplicitous role and behavior in patients with pancreatic cancer.

Bioengineering skin using mechanisms of regeneration and repair

The development and use of artificial skin in treating acute and chronic wounds has, over the last 30 years, advanced from a scientific concept to a series of commercially viable products. Many important clinical milestones have been reached and the number of artificial skin substitutes licensed for clinical use is growing, but they have yet to replace the current "gold standard" of an autologous skin graft. Currently available skin substitutes often suffer from a range of problems that include poor integration (which in many cases is a direct result of inadequate vascularisation), scarring at the graft margins and a complete lack of differentiated structures. The ultimate goal for skin tissue engineers is to regenerate skin such that the complete structural and functional properties of the wounded area are restored to the levels before injury. New synthetic biomaterials are constantly being developed that may enable control over wound repair and regeneration mechanisms by manipulating cell adhesion, growth and differentiation and biomechanics for optimal tissue development. In this review, the clinical developments in skin bioengineering are discussed, from conception through to the development of clinically viable products. Central to the discussion is the development of the next generation of skin replacement therapy, the success of which is likely to be underpinned with our knowledge of wound repair and regeneration.

Tissue engineering of replacement skin: the crossroads of biomaterials, wound healing, embryonic development, stem cells and regeneration

Advanced therapies combating acute and chronic skin wounds are likely to be brought about using our knowledge of regenerative medicine coupled with appropriately tissue-engineered skin substitutes. At the present time, there are no models of an artificial skin that completely replicate normal uninjured skin. Natural biopolymers such as collagen and fibronectin have been investigated as potential sources of biomaterial to which cells can attach. The first generation of degradable polymers used in tissue engineering were adapted from other surgical uses and have drawbacks in terms of mechanical and degradation properties. This has led to the development of synthetic degradable gels primarily as a way to deliver cells and/or molecules in situ, the so-called smart matrix technology. Tissue or organ repair is usually accompanied by fibrotic reactions that result in the production of a scar. Certain mammalian tissues, however, have a capacity for complete regeneration without scarring; good examples include embryonic or foetal skin and the ear of the MRL/MpJ mouse. Investigations of these model systems reveal that in order to achieve such complete regeneration, the inflammatory response is altered such that the extent of fibrosis and scarring is diminished. From studies on the limited examples of mammalian regeneration, it may also be possible to exploit such models to further clarify the regenerative process. The challenge is to identify the factors and cytokines expressed during regeneration and incorporate them to create a smart matrix for use in a skin equivalent. Recent advances in the use of DNA microarray and proteomic technology are likely to aid the identification of such molecules. This, coupled with recent advances in non-viral gene delivery and stem cell technologies, may also contribute to novel approaches that would generate a skin replacement whose materials technology was based not only upon intelligent design, but also upon the molecules involved in the process of regeneration.

Tgf-beta antisense therapy increases angiogenic potential in human keratinocytes in vitro

BACKGROUND

Transforming growth factor-beta (TGF-beta) has been identified as an important component of wound healing. Recent developments in molecular therapy offer exciting prospects for the modulation of wound healing, specifically those targeting TGF-beta. The purpose of this study was to analyze the effect of TGF-beta targeting on the expression of angiogenic vascular endothelial growth factor (VEGF), a key regulator of angiogenesis, and in vitro angiogenic activity.

METHODS

Expression of angiogenic VEGF in tissue samples from chronic dermal wounds was investigated by immunohistochemistry. The effect of TGF-beta targeting using antisense oligonucleotides on the expression of VEGF was analyzed by ELISA and RT-PCR in cultured human keratinocytes. Human endothelial cells (EC) were grown in conditioned medium produced from the treated keratinocytes. EC migration was measured using a modified Boyden chamber, EC tube formation was analyzed under the light microscope.

RESULTS

Immunohistochemical investigation demonstrated a decreased expression of VEGF protein in tissue samples from chronic dermal wounds compared to normal human skin. Antisense TGF-beta oligonucleotide treatment upregulated VEGF secretion in vitro. Addition of conditioned medium from TGF-beta antisense-treated keratinocytes resulted in an increase of endothelial cell migration and tube formation.

CONCLUSIONS

Our results demonstrate that TGF-beta antisense oligonucleotide technology may be a potential therapeutic option for stimulation of angiogenesis in chronic wounds.

Scar wars: is TGFbeta the phantom menace in scleroderma?

The autoimmune disease scleroderma (systemic sclerosis (SSc)) is characterized by extensive tissue fibrosis, causing significant morbidity. There is no therapy for the fibrosis observed in SSc; indeed, the underlying cause of the scarring observed in this disease is unknown. Transforming growth factor-β (TGFβ) has long been hypothesized to be a major contributor to pathological fibrotic diseases, including SSc. Recently, the signaling pathways through which TGFβ activates a fibrotic program have been elucidated and, as a consequence, several possible points for anti-fibrotic drug intervention in SSc have emerged.

Non-viral ocular gene therapy: potential ocular therapeutic avenues

Non-viral vectors for potential gene replacement and therapy have been developed in order to overcome the drawbacks of viral vectors. The diversity of non-viral vectors allows for a wide range of various products, flexibility of application, ease of use, low-cost of production and enhanced "genomic" safety. Using non-viral strategies, oligonucleotides (ODNs) can be delivered naked (less efficient) or entrapped in cationic lipids, polymers or peptides forming slow release delivery systems, which can be adapted according to the organ targeted and the therapy purposes. Tissue and cell internalization can be further enhanced by changing by physical or chemical means. Moreover, a specific vector can be selected according to disease course and intensity of manifestations fulfilling specific requirements such as the duration of drug release and its level along with cells and tissues specific targeting. From accumulating knowledge and experience, it appears that combination of several non-viral techniques may increase the efficacy and ensure the safety of these evolving and interesting gene therapy strategies.