In Vivo Assessment of a Manual Single Lumen Alternating Micro-Batch Hemodiafiltration (mSLAMB) System.

INTRODUCTION: The manual single lumen alternating micro-batch hemodiafiltration (mSLAMB) system is a closed-loop dialysis system designed to provide kidney support in emergency situations (e.g., fluid overload, hyperkalemia, acidemia). If done repeatedly in small batches and at high flow rates, this system was found to achieve clearance levels comparable to traditional renal replacement therapy (RRT). METHODS: Using a porcine model, uremic toxins and exogenous fluorescent tracer concentrations were successfully lowered within just 1 hour of treatment. RESULTS: With a maximal dialysate flow, mSLAMB can achieve decreases in serum potassium concentration of > 0.5 mmol/L/ hr. With the mSLAMB hemodiafiltration system, micro-batch processing was also successful in removing up to 250mL of ultrafiltrate in 8 cycles. CONCLUSION: This process could create a better fluid balance allowing for administering therapeutic fluids such as sodium bicarbonate in the clinic. Electrolyte imbalance and volume overload remain severe life-threatening emergencies in low resource settings, therefore mSLAMB should be explored further due to its modest vascular access requirements, low cost, and ability to be performed without electricity or batteries.

Immunomodulatory therapy using a pediatric dialysis system ameliorates septic shock in miniature pigs.

BACKGROUND: Application of the immunomodulatory selective cytopheretic device (SCD) to enhance renal replacement therapy and improve outcomes of acute kidney injury in pediatric patients is impeded by safety concerns. Therapy using a pediatric hemodialysis system could overcome these limitations. METHODS: Yucatan minipigs (8-15 kg) with induced septic shock underwent continuous hemodiafiltration with the CARPEDIEM™ pediatric hemodialysis system using regional citrate anticoagulation (RCA) with or without SCD (n = 5 per group). Circuit function plus hemodynamic and hematologic parameters were assessed for 6 h. RESULTS: SCD was readily integrated into the CARPEDIEM™ system and treatment delivered for 6 h without interference with pump operation. SCD-treated pigs maintained higher blood pressure (p = 0.009) commensurate with lesser degree of lactic acidosis (p = 0.008) compared to pigs only receiving hemodiafiltration. Renal failure occurred in untreated pigs while urine output was sustained with SCD therapy. Neutrophil activation levels and ss-SOFA scores at 6 h trended lower in the SCD-treated cohort. CONCLUSIONS: SCD therapy under RCA was safely administered using the CARPEDIEM™ pediatric hemodialysis system for up to 6 h and no circuit compatibility issues were identified. Sepsis progression and organ dysfunction was diminished with SCD treatment in this model supportive of therapeutic benefit of this immunomodulatory therapy. IMPACT: SCD therapy with regional citrate anticoagulation has the potential to be administered safely to patients weighing <20 kg using the Carpediem renal replacement therapy platform. Use of a renal replacement therapy platform designed specifically for neonates/infants overcomes safety concerns for delivery of SCD treatment in this population. SCD therapy using the Carpediem renal replacement therapy platform retained the suggestive efficacy seen in larger children and adults to reduce organ injury and dysfunction from sepsis.

Hemolytic Uremic Syndrome-Induced Acute Kidney Injury Treated via Immunomodulation with the Selective Cytopheretic Device.

INTRODUCTION: Shiga-toxin associated-hemolytic uremic syndrome (STEC-HUS) is a severe cause of acute kidney injury (AKI) in children. Although most children recover, about 5% die and 30% develop chronic renal morbidity. HUS pathophysiology includes activated neutrophils damaging vascular endothelial cells. Therapeutic immunomodulation of activated neutrophils may alter the progression of disease. We present 3 pediatric patients treated with the selective cytopheretic device (SCD). METHODS: We describe a 12 y.o. (patient 1) and two 2 y.o. twins (patients 2 and 3) with STEC-HUS requiring continuous renal replacement therapy (CRRT) who were enrolled in two separate studies of the SCD. RESULTS: Patient 1 presented with STEC-HUS causing AKI and multisystem organ failure and received 7 days of SCD and CRRT treatment. After SCD initiation, the patient had gradual recovery of multi-organ dysfunction, with normal kidney and hematologic parameters at 60-day follow-up. Patients 2 and 3 presented with STEC-HUS with AKI requiring dialysis. Each received 24 h of SCD therapy. Thereafter, both gradually improved, with normalization (patient 2) and near-normalization (patient 3) of kidney function at 60-day follow-up. CONCLUSION: Immunomodulatory treatment with the SCD was associated with improvements in multisystem stigmata of STEC-HUS-induced AKI and was well-tolerated without any device-related adverse events.

Embedding of Precision-Cut Lung Slices in Engineered Hydrogel Biomaterials Supports Extended Ex Vivo Culture.

Maintaining the three-dimensional architecture and cellular complexity of lung tissue ex vivo can enable elucidation of the cellular and molecular pathways underlying chronic pulmonary diseases. Precision-cut lung slices (PCLS) are one human-lung model with the potential to support critical mechanistic studies and early drug discovery. However, many studies report short culture times of 7-10 days. Here, we systematically evaluated poly(ethylene glycol)-based hydrogel platforms for the encapsulation of PCLS. We demonstrated the ability to support ex vivo culture of embedded PCLS for at least 21 days compared with control PCLS floating in media. These customized hydrogels maintained PCLS architecture (no difference), viability (4.7-fold increase, P < 0.0001), and cellular phenotype as measured by SFTPC (1.8-fold increase, P < 0.0001) and vimentin expression (no change) compared with nonencapsulated controls. Collectively, these results demonstrate that hydrogel biomaterials support the extended culture times required to study chronic pulmonary diseases ex vivo using PCLS technology.

Glycosylation facilitates transdermal transport of macromolecules.

Stratum corneum, the outermost layer of skin, allows transport of only low-molecular weight (<500) lipophilic solutes. Here, we report a surprising finding that avicins (Avs), a family of naturally occurring glycosylated triterpenes with a molecular weight > 2,000, exhibit skin permeabilities comparable to those of small hydrophobic molecules, such as estradiol. Systematic fragmentation of the Av molecule shows that deletion of the outer monoterpene results in a 62% reduction in permeability, suggesting an important role for this motif in skin permeation. Further removal of the tetrasaccharide residue results in a further reduction of permeability by 79%. These results, taken in sum, imply that synergistic effects involving both hydrophobic and hydrophilic residues may hold the key in facilitating translocation of Avs across skin lipids. In addition to exhibiting high permeability, Avs provided moderate enhancements of skin permeability of estradiol and polysaccharides, including dextran and inulin but not polyethylene glycol.

Immunomodulatory effects of a cell processing device to ameliorate dysregulated hyperinflammatory disease states.

Cell directed therapy is an evolving therapeutic approach to treat organ dysfunction arising from hyperinflammation and cytokine storm by processing immune cells in an extracorporeal circuit. To investigate the mechanism of action of the Selective Cytopheretic Device (SCD), in vitro blood circuits were utilized to interrogate several aspects of the immunomodulatory therapy. SCD immunomodulatory activity is due to its effects on circulating neutrophils and monocytes in a low ionized calcium (iCa, Ca2+) blood circuit. Activated neutrophils adhere to the SCD fibers and degranulate with release of the constituents of their exocytotic vesicles. Adhered neutrophils in the low iCa environment display characteristics of apoptotic senescence. These neutrophils are subsequently released and returned back to circulation, demonstrating a clear potential for in vivo feedback. For monocytes, SCD treatment results in the selective adhesion of more pro-inflammatory subsets of the circulating monocyte pool, as demonstrated by both cell surface markers and cytokine secretory rates. Once bound, over time a subset of monocytes are released from the membrane with a less inflammatory functional phenotype. Similar methods to interrogate mechanism in vitro have been used to preliminarily confirm comparable findings in vivo. Therefore, the progressive amelioration of circulating leukocyte activation and immunomodulation of excessive inflammation observed in SCD clinical trials to date is likely due to this continuous autologous leukocyte processing.

Increasing Eligibility to Transplant Through the Selective Cytopheretic Device: A Review of Case Reports Across Multiple Clinical Conditions.

A stable, minimum physiological health status is required for patients to qualify for transplant or artificial organ support eligibility to ensure the recipient has enough reserve to survive the perioperative transplant period. Herein, we present a novel strategy to stabilize and improve patient clinical status through extracorporeal immunomodulation of systemic hyperinflammation with impact on multiple organ systems to increase eligibility and feasibility for transplant/device implantation. This involves treatment with the selective cytopheretic device (SCD), a cell-directed extracorporeal therapy shown to adhere and immunomodulate activated neutrophils and monocytes toward resolution of systemic inflammation. In this overview, we describe a case series of successful transition of pediatric and adult patients with multiorgan failure to successful transplant/device implantation procedures by treatment with the SCD in the following clinical situations: pediatric hemophagocytic lymphohistiocytosis, and adult hepatorenal and cardiorenal syndromes. Application of the SCD in these cases may represent a novel paradigm in increasing clinical eligibility of patients to successful transplant outcomes.

Surface functionality as a means to impact polymer nanoparticle size and structure.

When polymeric nanoparticles (NPs) are formed by nanoprecipitation, which is a nucleation-growth process, the control over size requires changing the polymer concentration or solvent composition. Here, we demonstrate that the NP size can be controlled independent of polymer variables by introducing a polyelectrolyte (PE) in the aqueous phase. PEs that exhibit hydrogen bonding (H-bonding) yield a reduction in NP size, whereas PEs that do not possess this characteristic promote the formation of larger NPs. The observed effect can be attributed to the formation of a diffusional barrier around the NP in the form of a dense shell. This principle of controlling NP size is not limited to polymers and can also be employed in the production of lipid NPs.

Cell-based approaches for the treatment of systemic inflammation.

Acute and chronic solid organ failures are costly disease processes with high mortality rates. Inflammation plays a central role in both acute and chronic organ failure, including heart, lung and kidney. In this regard, new therapies for these disorders have focused on inhibiting the mediators of inflammation, including cytokines and free radicals, with little or no success in clinical studies. Recent novel treatment strategies have been directed to cell-based rather than mediator-based approaches, designed to immunomodulate the deleterious effects of inflammation on organ function. One approach, cell therapy, replaces cells that were damaged in the acute or chronic disease process with stem/progenitor technology, to rebalance excessive inflammatory states. As an example of this approach, the use of an immunomodulatory role of renal epithelial progenitor cells to treat acute renal failure (ARF) and multiorgan failure arising from acute kidney injury is reviewed. A second therapeutic pathway, cell processing, does not incorporate stem/progenitor cells in the device, but rather biomimetic materials that remove and modulate the primary cellular components, which promote the worsening organ tissue injury associated with inflammation. The use of an immunomodulating leukocyte selective cytopheretic inhibitory device is also reviewed as an example of this cell processing approach. Both of these unconventional strategies have shown early clinical efficacy in pilot clinical trials and may transform the therapeutic approach to organ failure disorders.

Selective cytopheretic inhibitory device with regional citrate anticoagulation and portable sorbent dialysis.

Selective cytopheretic inhibitory device (SCD) therapy is an immunomodulatory treatment provided by a synthetic biomimetic membrane in an extracorporeal circuit, which has shown promise in preclinical large animal models of severe sepsis as well as in clinical trials treating patients with acute kidney injury and multiple organ failure. During SCD therapy, citrate is administered to lower ionized calcium levels in blood for anticoagulation and inhibition of leukocyte activation. Historically, citrate has been known to interfere with sorbent dialysis, therefore, posing a potential issue for the use of SCD therapy with a portable dialysis system. This sorbent dialysis SCD (sorbent SCD) would be well suited for battlefield and natural disaster applications where the water supply for standard dialysis is limited, and the types of injuries in those settings would benefit from SCD therapy. In order to explore the compatibility of sorbent and SCD technologies, a uremic porcine model was tested with the Allient sorbent dialysis system (Renal Solutions Incorporated, Fresenius Medical Care, Warrendale, PA, USA) and concurrent SCD therapy with regional citrate anticoagulation. The hypothesis to be assessed was whether the citrate load required by the SCD could be metabolized prior to recirculation from systemic blood back into the therapeutic circuit. Despite the fact that the sorbent SCD maintained urea clearance without any adverse hematologic events, citrate load for SCD therapy caused an interaction with the sorbent column resulting in elevated, potentially toxic aluminum levels in dialysate and in systemic blood. Alternative strategies to implement sorbent-SCD therapy will be required, including development of alternate urease-sorbent column binding chemistry or further changes to the sorbent-SCD therapeutic circuit along with determining the minimum citrate concentration required for efficacious SCD treatment.

Estimating Changes in Glomerular Filtration Rate With Fluorescein Isothiocyanate-Sinistrin During Renal Replacement Therapy.

Excreted exclusively by the kidneys, fluorescein isothiocyanate (FITC)-sinistrin can be used to measure glomerular filtration rate (GFR) and is detectable transdermally. Determination of changes in native kidney GFR (NK-GFR) in patients with acute kidney injury, particularly during continuous renal replacement therapy, improves clinical decision-making capability. To test feasibility of measuring changes in NK-GFR during CRRT with FITC-sinistrin, in vitro circuits (n = 2) were utilized to simultaneously clear FITC-sinistrin by removal of ultrafiltrate at varying rates, simulating kidney function, and by dialysis at a constant rate. Clearance calculated by fluorescence-measuring devices on the circuit showed good agreement with clearance calculated from assay of fluid samples ( R2 = 0.949). In vivo feasibility was studied by dialyzing anesthetized pigs (n = 3) and measuring FITC-sinistrin clearance during progression from normal, to unilaterally, then bilaterally nephrectomized. FITC-sinistrin clearance was reduced in vitro , when ultrafiltrate was decreased or with successive nephrectomies in vivo . Transdermal readers showed 100% sensitivity in detecting a decrease in NK-GFR in pigs with a bias of 6.5 ± 13.4% between transdermal-derived GFR (tGFR) and plasma-measured methods determining proportional changes in clearance. Clearance of FITC-sinistrin by dialysis remained consistent. In patients receiving a constant dialysis prescription, transdermal measurement of FITC-sinistrin can detect relative changes in NK-GFR.

Transdermal Detection of MB-102 and Correlation to Meropenem Pharmacokinetics During Continuous Renal Replacement Therapy: In Vivo Results.

Critically ill patients undergoing continuous renal replacement therapy (CRRT) have medical conditions requiring extensive pharmacotherapy. Continuous renal replacement therapy impacts drug disposition. Few data exist regarding drug dosing requirements with contemporary CRRT modalities and effluent rates. The practical limitations of pharmacokinetic studies requiring numerous plasma and effluent samples, and lack of generalizability of observations from specific CRRT prescriptions, highlight gaps in bedside assessment of CRRT drug elimination and individualized dosing needs. We employed a porcine model using transdermal fluorescence detection of the glomerular filtration rate fluorescent tracer agent MB-102, with the aim to assess the relationship between systemic exposure of MB-102 and meropenem during CRRT. Animals underwent bilateral nephrectomies and received intravenous bolus doses of MB-102 and meropenem. Once MB-102 equilibrated in the animal, CRRT was initiated. Continuous renal replacement therapy prescriptions comprised four combinations of blood pump (low versus high) and effluent (low versus high) flow rates. Changes in transdermal detected MB-102 clearance occurred immediately with a change in CRRT rates. Blood side meropenem clearance mirrored transdermal MB-102 clearance ( r2 : 0.95-0.97, p value all <0.001). We suggest transdermal MB-102 clearance provides real-time personalized assessment of drug elimination and could optimize prescription of drugs for critically ill patients requiring CRRT.

Cell-based strategies for the treatment of kidney dysfunction: a review.

Conventional treatment of acute and chronic renal diseases has focused on solute removal. Novel strategies aim to treat the multifactorial disease states of acute kidney injury and chronic kidney disease by mitigating inflammation. Cell-based technologies for the treatment of kidney dysfunction fall under two broad categories: cell therapy and cell processing. Cell therapy utilizes cells that are isolated, cultured outside of the body, and reintroduced as therapy, leveraging beneficial metabolic and synthetic functions. For example, renal tubule cells have been used to provide gluconeogenesis, ammoniagenesis, metabolism of glutathione, catabolism of important peptide hormones, growth factors, and cytokines critical to multiorgan homeostasis and immunomodulation to treat renal dysfunction. Cell processing focuses on altering the characteristics of cell populations inside the body to provide therapy. The selective cytopheretic device is an example of this novel therapeutic strategy that aims to modulate the innate immune response during organ dysfunction, additional organ injury, by binding and deactivating leukocytes. In this review, both cell therapy and cell processing approaches will be discussed in the context of acute kidney injury and chronic renal disease.

The effect of silica nanoparticle-modified surfaces on cell morphology, cytoskeletal organization and function.

Chemical and morphological characteristics of a biomaterial surface are thought to play an important role in determining cellular differentiation and apoptosis. In this report, we investigate the effect of nanoparticle (NP) assemblies arranged on a flat substrate on cytoskeletal organization, proliferation and metabolic activity on two cell types, Bovine aortic endothelial cells (BAECs) and mouse calvarial preosteoblasts (MC3T3-E1). To vary roughness without altering chemistry, glass substrates were coated with monodispersed silica nanoparticles of 50, 100 and 300 nm in diameter. The impact of surface roughness at the nanoscale on cell morphology was studied by quantifying cell spreading, shape, cytoskeletal F-actin alignment, and recruitment of focal adhesion complexes (FAC) using image analysis. Metabolic activity was followed using a thiazolyl blue tetrazolium bromide assay. In the two cell types tested, surface roughness introduced by nanoparticles had cell type specific effects on cell morphology and metabolism. While BAEC on NP-modified substrates exhibited smaller cell areas and fewer focal adhesion complexes compared to BAEC grown on glass, MC3T3-E1 cells in contrast exhibited larger cell areas on NP-modified surfaces and an increased number of FACs, in comparison to unmodified glass. However, both cell types on 50 nm NP had the highest proliferation rates (comparable to glass control) whereas cells grown on 300 nm NP exhibited inhibited proliferation. Interestingly, for both cell types surface roughness promoted the formation of long, thick F-actin fibers, which aligned with the long axis of each cell. These findings are consistent with our earlier result that osteogenic differentiation of human mesenchymal progenitor cells is enhanced on NP-modified surfaces. Our finding that nanoroughness, as imparted by nanoparticle assemblies, effects cellular processes in a cell specific manner, can have far reaching consequences on the development of "smart" biomaterials especially for directing stem cell differentiation.

Regenerative Medicine and Immunomodulatory Therapy: Insights From the Kidney, Heart, Brain, and Lung.

Regenerative medicine was initially focused on tissue engineering to replace damaged tissues and organs with constructs derived from cells and biomaterials. More recently, this field of inquiry has expanded into exciting areas of translational medicine modulating the body's own endogenous processes, to prevent tissue damage in organs and to repair and regenerate these damaged tissues. This review will focus on recent insights derived from studies in which the manipulation of the innate immunologic system may diminish acute kidney injury and enhance renal repair and recovery without the progression to chronic kidney disease and renal failure. The manner in which these interventions may improve acute and chronic organ dysfunction, including the heart, brain, and lung, will also be reviewed.

Bioengineered Renal Cell Therapy Device for Clinical Translation.

The bioartificial renal epithelial cell system (BRECS) is a cell-based device to treat acute kidney injury through renal cell therapy from an extracorporeal circuit. To enable widespread implementation of cell therapy, the BRECS was designed to be cryopreserved as a complete device, cryostored, cryoshipped to an end-use site, thawed as a complete device, and employed in a therapeutic extracorporeal hemofiltration circuit. This strategy overcomes storage and distribution issues that have been previous barriers to cell therapy. Previous BRECS housings produced by computer numerical control (CNC) machining, a slow process taking hours to produce one bioreactor, was also prohibitively expensive (>$600/CNC-BRECS); major obstacles to mass production. The goal of this study was to produce a BRECS to be mass produced by injection-molded BRECS (IM-BRECS), decreasing cost (<$20/unit), and improving manufacturing speed (hundreds of units/h), while maintaining the same cell therapy function as the previous CNC-BRECS, first evaluated through prototypes produced by stereolithography BRECS (SLA-BRECS). The finalized IM-BRECS design had a significantly lower fill volume (10 ml), mass (49 g), and footprint (8.5 cm × 8.5 cm × 1.5 cm), and was demonstrated to outperform the previous BRECS designs with respect to heat transfer, significantly improving control of cooling during cryopreservation and reducing thaw times during warming. During in vitro culture, IM-BRECS performed similarly to previous CNC-BRECS with respect to cell metabolic activity (lactate production, oxygen consumption, and glutathione metabolism) and amount of cells supported.

A bio-artificial renal epithelial cell system conveys survival advantage in a porcine model of septic shock.

Renal cell therapy using the hollow fiber based renal assist device (RAD) improved survival time in an animal model of septic shock (SS) through the amelioration of cardiac and vascular dysfunction. Safety and ability of the RAD to improve clinical outcomes was demonstrated in a Phase II clinical trial, in which patients had high prevalence of sepsis. Even with these promising results, clinical delivery of cell therapy is hampered by manufacturing hurdles, including cell sourcing, large-scale device manufacture, storage and delivery. To address these limitations, the bioartificial renal epithelial cell system (BRECS) was developed. The BRECS contains human renal tubule epithelial cells derived from adult progenitor cells using enhanced propagation techniques. Cells were seeded onto trabeculated disks of niobium-coated carbon, held within cryopreservable, perfusable, injection-moulded polycarbonate housing. The study objective was to evaluate the BRECS in a porcine model of SS to establish conservation of efficacy after necessary cell sourcing and design modifications; a pre-clinical requirement to move back into clinical trials. SS was incited by peritoneal injection of E. coli simultaneous to insertion of BRECS (n=10) or control (n=15), into the ultrafiltrate biofeedback component of an extracorporeal circuit. Comparable to RAD, prolonged survival of the BRECS cohort was conveyed through stabilization of cardiac output and vascular leak. In conclusion, the demonstration of conserved efficacy with BRECS therapy in a porcine SS model represents a crucial step toward returning renal cell therapy to the clinical setting, initially targeting ICU patients with acute kidney injury requiring continuous renal replacement therapy. Copyright © 2014 John Wiley & Sons, Ltd.

Development of a wearable bioartificial kidney using the Bioartificial Renal Epithelial Cell System (BRECS).

Cell therapy for the treatment of renal failure in the acute setting has proved successful, with therapeutic impact, yet development of a sustainable, portable bioartificial kidney for treatment of chronic renal failure has yet to be realized. Challenges in maintaining an anticoagulated blood circuit, the typical platform for solute clearance and support of the biological components, have posed a major hurdle in advancement of this technology. This group has developed a Bioartificial Renal Epithelial Cell System (BRECS) capable of differentiated renal cell function while sustained by body fluids other than blood. To evaluate this device for potential use in end-stage renal disease, a large animal model was established that exploits peritoneal dialysis fluid for support of the biological device and delivery of cell therapy while providing uraemic control. Anephric sheep received a continuous flow peritoneal dialysis (CFPD) circuit that included a BRECS. Sheep were treated with BRECS containing 1 × 108 renal epithelial cells or acellular sham devices for up to 7 days. The BRECS cell viability and activity were maintained with extracorporeal peritoneal fluid circulation. A systemic immunological effect of BRECS therapy was observed as cell-treated sheep retained neutrophil oxidative activity better than sham-treated animals. This model demonstrates that use of the BRECS within a CFPD circuit embodies a feasible approach to a sustainable and effective wearable bioartificial kidney. Copyright © 2016 John Wiley & Sons, Ltd.

Seeding of corneal wounds by epithelial cell transfer from micropatterned PDMS contact lenses.

Persistent corneal wounds result from numerous eye disorders, and to date, available treatments often fail to accelerate reepithelialization, the key initial step in wound healing. To speed reepithelialization, we explored a cell-transfer transplant method utilizing polydimethylsiloxane (PDMS) contact lenses to deliver epithelial cells derived from limbal explants directly within a corneal wound. Human primary epithelial cells and an immortalized corneal epithelial cell line (HCE-SV40) grew well on PDMS contact lenses and their morphology and growth rates where similar to cells grown on tissue culture polystyrene. To initially study cell transfer from PDMS, HCE-SV40 cells were seeded onto PDMS with or without micropatterned posts. After a day in culture, HCE-SV40 cells attached to the unpatterned PDMS uniformly, whereas on micropatterned PDMS they appeared to attach primarily between posts. The cell-covered PDMS contacts were then placed cell-side down onto tissue culture plastic and, after 1, 2, or 3 days, the PDMS contact was removed and the transferred cells were trypsinized and counted. Micropatterned PDMS contact lenses with 100-microm-diameter posts and a post height of 40 microm transferred three times as many cells as unpatterned PDMS. Cell transfer to a wounded cornea was tested in a pig cornea organ culture model de-epithelialized by alkali treatment. Post micropatterned PDMS contact lenses were seeded with labeled HCE-SV40 cells at a density 50,000 cells/cm2 and applied to the wounded pig corneas. After 24, 48, or 96 h of application, PDMS contact lenses were removed, corneas fixed with formaldehyde, and sectioned. After 48 h, epithelial cells transferred from post micropatterned contact lenses to provide 35% epithelial coverage of denuded pig corneas; after 96 h coverage was 65%. We conclude that cell transfer from epithelial-coated PDMS contact lenses micropatterned with posts provides a promising approach to reepithelialize corneal surfaces.

Investigation of the transdermal transport of charged local anesthetics in the presence of triterpene saponin glycosides.

Percutaneous absorption and transdermal delivery of water-soluble drugs have proven to be challenging due to their low permeability through skin. Avicins which are triterpene saponin glycosides (TSGs) derived from the desert plant Acacia victoriae have not been investigated to date as chemical penetration enhancers due to their higher molecular weight (MW 2,000 Da). It was recently shown that avicins exhibit remarkable mobility across skin lipids in spite of their large size due to their unique chemical structure. In this study, the permeation of local anesthetics, lidocaine-HCl, prilocaine-HCl, and bupivacaine-HCL from aqueous vehicle, across full-thickness porcine skin was investigated in the presence of F094-a mixture of avicins. F094 was capable of enhancing the permeability of all three anesthetics from aqueous formulations at extremely low concentrations ranging from 0.1 to 1 % w/v. The enhancement, which ranged from 2- to 5-fold, was surprisingly independent of molecular weight of the anesthetics and showed clear correlation with aqueous phase solubility of the anesthetics. Since F094 was found to have no impact on the octanol/water partition coefficients of the anesthetics, this suggests that TSGs like avicins most likely impact the aqueous pathways (pericellular/pores within lipids) and as such represent an alternative means of enhancing the transdermal transport of charged drugs from water-based formulations.