1
|
Sapino S, Chindamo G, Peira E, Chirio D, Foglietta F, Serpe L, Vizio B, Gallarate M. Development of ARPE-19-Equipped Ocular Cell Model for In Vitro Investigation on Ophthalmic Formulations. Pharmaceutics 2023; 15:2472. [PMID: 37896232 PMCID: PMC10610172 DOI: 10.3390/pharmaceutics15102472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/03/2023] [Accepted: 10/13/2023] [Indexed: 10/29/2023] Open
Abstract
Repeated intravitreal (IVT) injections in the treatment of retinal diseases can lead to severe complications. Developing innovative drug delivery systems for IVT administration is crucial to prevent adverse reactions, but requires extensive investigation including the use of different preclinical models (in vitro, ex vivo and in vivo). Our previous work described an in vitro tricompartmental ocular flow cell (TOFC) simulating the anterior and posterior cavities of the human eye. Based on promising preliminary results, in this study, a collagen scaffold enriched with human retinal pigmented epithelial cells (ARPE-19) was developed and introduced into the TOFC to partially mimic the human retina. Cells were cultured under dynamic flow conditions to emulate the posterior segment of the human eye. Bevacizumab was then injected into the central compartment of the TOFC to treat ARPE-19 cells and assess its effects. The results showed an absence of cytotoxic activity and a significant reduction in VEGF fluorescent signal, underscoring the potential of this in vitro model as a platform for researching new ophthalmic formulations addressing the posterior eye segment, eventually decreasing the need for animal testing.
Collapse
Affiliation(s)
- Simona Sapino
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (G.C.); (D.C.); (F.F.); (L.S.); (M.G.)
| | - Giulia Chindamo
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (G.C.); (D.C.); (F.F.); (L.S.); (M.G.)
| | - Elena Peira
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (G.C.); (D.C.); (F.F.); (L.S.); (M.G.)
| | - Daniela Chirio
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (G.C.); (D.C.); (F.F.); (L.S.); (M.G.)
| | - Federica Foglietta
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (G.C.); (D.C.); (F.F.); (L.S.); (M.G.)
| | - Loredana Serpe
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (G.C.); (D.C.); (F.F.); (L.S.); (M.G.)
| | - Barbara Vizio
- Department of Medical Sciences, University of Turin, Via Genova 3, 10126 Turin, Italy;
| | - Marina Gallarate
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (G.C.); (D.C.); (F.F.); (L.S.); (M.G.)
| |
Collapse
|
2
|
Experimental assessment of the performance of vitreous cutters with fluids with different rheological properties. Graefes Arch Clin Exp Ophthalmol 2021; 259:1113-1121. [PMID: 33394160 DOI: 10.1007/s00417-020-05061-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/02/2020] [Accepted: 12/21/2020] [Indexed: 10/22/2022] Open
Abstract
PURPOSE To assess the influence of rheological properties of an artificial vitreous (AV) on the performance of double-blade (DB) and single-blade (SB) guillotine vitreous cutters, with 23-, 25-, and 27-gauge (G) probes. METHODS We evaluate the aspiration flow rate, using an optical method, based on image processing. Experiments are conducted using ten viscoelastic vitreous phantoms, with different properties that are measured with rheological tests. RESULTS Aspiration rate strongly varies with fluid properties. Regardless of cutter geometry and operational conditions, the flow rate significantly decreases as vitreous viscosity and elasticity increase. CONCLUSIONS All tested vitreous probes are very sensitive to changes in fluid rheology. SB cutters produce smaller flow rates compared with DB ones of the same caliber; however, they are less sensitive to fluid properties at low aspiration pressures. The use of vitreous substitutes for test performance guarantees comparability between flow rate results achieved with different vitrectomy systems operating in different media. This outcome is further confirmed by the low values of estimated flow rate relative errors.
Collapse
|
3
|
Stocchino A, Nepita I, Repetto R, Dodero A, Castellano M, Ferrara M, Romano MR. Fluid Dynamic Assessment of Hypersonic and Guillotine Vitrectomy Probes in Viscoelastic Vitreous Substitutes. Transl Vis Sci Technol 2020; 9:9. [PMID: 32821506 PMCID: PMC7409383 DOI: 10.1167/tvst.9.6.9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 03/11/2020] [Indexed: 12/18/2022] Open
Abstract
Purpose To assess the fluidics of 23-gauge (G) large-port (L) and tear drop-port (TD) hypersonic vitrectomy probes (HVPs) compared with guillotine vitrectomy probes (GVPs) of various calibers (23G, 25G, and 27G) and geometries (single and double blades). Also, to identify the working parameters that provide the best balance between acceleration and flow rate, and, for HVPs, to measure temperature variations in the fluid. Methods We used particle image velocimetry to measure flow fields in balanced salt solution and viscoelastic artificial vitreous. We analyzed acceleration, kinetic energy, and volumetric flux. The parameters considered were vacuum pressure, ultrasound stroke, and cut rate. Temperature measurements were taken using an infrared thermal camera. Results The flow rate was significantly higher for HVPs than GVPs. With both probes, flow rate and acceleration increased with vacuum pressure. Flow rate depended weakly on the ultrasound stroke or cut rate. In HVPs, the acceleration peaked at a stroke of 30 µm, whereas in GVPs it peaked at a cutting rate of 4000 to 5000 cuts per minute (cpm). The HPV/TD combination generated higher flow rates and lower accelerations than did HPV/L. The increase in temperature was small. Conclusions Under the present experimental setup and medium, HVPs offered better fluidics compared with GVPs in terms of flow and acceleration; however, the flow structure for HVPs is more complicated and unsteady. The HPV/TD combination produced larger flows than did the HPV/L combination and slightly smaller accelerations. HPVs generated a small temperature increase. Translational Relevance In the tested artificial vitreous, HVPs were found to be more efficient in terms of generating lower acceleration for a given flow rate. The slight increase in temperature observed with HVPs is unlikely to be clinically significant.
Collapse
Affiliation(s)
- Alessandro Stocchino
- Department of Civil, Chemical and Environmental Engineering, University of Genoa, Genoa, Italy
| | - Irene Nepita
- Department of Civil, Chemical and Environmental Engineering, University of Genoa, Genoa, Italy
| | - Rodolfo Repetto
- Department of Civil, Chemical and Environmental Engineering, University of Genoa, Genoa, Italy
| | - Andrea Dodero
- Department of Chemistry and Industrial Chemistry, University of Genoa, Genoa, Italy
| | - Maila Castellano
- Department of Chemistry and Industrial Chemistry, University of Genoa, Genoa, Italy
| | | | - Mario R Romano
- Eye Center, Humanitas Gavazzeni-Castelli, Bergamo, Italy.,Department of Biomedical Sciences, Humanitas University, Milano, Italy
| |
Collapse
|
4
|
He X, Yuan Z, Kao W, Miller D, Li SK, Park YC. Size-Exclusive Nanoporous Biodegradable PLGA Capsules for Drug Delivery Implants and In Vivo Stability in the Posterior Segment. ACS APPLIED BIO MATERIALS 2020; 3:1722-1729. [PMID: 35021661 DOI: 10.1021/acsabm.0c00027] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The current standard of care for posterior segment eye diseases, such as neovascular age-related macular degeneration, diabetic macular edema, is frequent intravitreal injections or sustained-release drug implants. Intravitreal injections have a low incidence of serious complications such as retinal detachment, endophthalmitis, iatrogenic traumatic cataract, or iridocyclitis and injection-site reactions. However, there is a significant burden to the patient, the patient's family, and the health system because current intravitreal therapies require between every 4 and 12 week administration over many years. Drug implants have side effects due to the burst release of the drugs, and their release cannot be easily controlled after implantation. We have developed a size-exclusive nanoporous biodegradable PLGA capsule for dosage-controllable drug delivery implants. We have optimized the nanoporous structure by tuning the ratio between porogen and high molecular weight PLGA and tested the stability against passive leakage of the liposomal drug (1-2 μm) and the safety in vivo rabbit eyes for 6 months. Our results suggest that PLGA implants made of the nanoporous PLGA sheet can selectively release drug molecules, keeping the liposomal drug inside. In addition, the implant was biocompatible, causing no inflammation and foreign body response when implanted for 6 months. Overall, the implant shows great potential for on-demand dose-controllable drug release applications.
Collapse
Affiliation(s)
| | | | | | - Daniel Miller
- Cincinnati Eye Institute, Cincinnati, Ohio 45242, United States
| | - S Kevin Li
- College of Pharmacy, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | | |
Collapse
|
5
|
Thakur SS, Shenoy SK, Suk JS, Hanes JS, Rupenthal ID. Validation of hyaluronic acid-agar-based hydrogels as vitreous humor mimetics for in vitro drug and particle migration evaluations. Eur J Pharm Biopharm 2020; 148:118-125. [PMID: 31981693 DOI: 10.1016/j.ejpb.2020.01.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 01/16/2020] [Accepted: 01/19/2020] [Indexed: 12/26/2022]
Abstract
Artificial vitreous humor holds immense potential for use in in vitro intravitreal drug delivery assays. In this study, we investigated rheological properties and drug or nanoparticle migration in hyaluronic acid (HA) - agar based hydrogels and compared these characteristics with bovine vitreous humor. Gel compositions identified in literature containing HA (0.7-5.0 mg/ml) and agar (0.95-4.0 mg/ml) were classified as either high (VH), medium (VM) or low (VL) polymer load. Viscoelastic behavior was evaluated using oscillatory rheology, and migration of differently sized and charged polystyrene nanoparticles (NPs) through the different gels was determined via multiple particle tracking. Comparable rheological behaviour was observed between VL and bovine vitreous. Tracking evaluations revealed that increasing particle size and gel viscosity slowed NP migration. Additionally, 100 nm anionic NPs migrated slower than neutral NPs in VL and VM, while cationic NPs were immobile in all gels. Finally, distribution and clearance of sodium fluorescein was used to model drug mobility through the gels using a custom-built eye model. Flow and angular movement only influenced drug migration in VL and VM, but not VH. Finally, VL and VM demonstrated to have the most similar sodium fluorescein clearance to that of bovine vitreous humor. Together, these evaluations demonstrate that low viscosity HA-agar gels can be used to approximate nanoparticle and drug migration through biological vitreous humor.
Collapse
Affiliation(s)
- Sachin S Thakur
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
| | - Siddharth K Shenoy
- Center for Nanomedicine, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, 400 North Broadway, Baltimore, MD 21231, USA; Department of Ophthalmology, Johns Hopkins University School of Medicine, 400 North Broadway, Baltimore, MD 21231, USA
| | - Jung Soo Suk
- Center for Nanomedicine, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, 400 North Broadway, Baltimore, MD 21231, USA; Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Ophthalmology, Johns Hopkins University School of Medicine, 400 North Broadway, Baltimore, MD 21231, USA
| | - Justin S Hanes
- Center for Nanomedicine, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, 400 North Broadway, Baltimore, MD 21231, USA; Department of Pharmacology & Molecular Sciences, Johns Hopkins University School of Medicine, 400 North Broadway, Baltimore, MD 21231, USA; Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Ophthalmology, Johns Hopkins University School of Medicine, 400 North Broadway, Baltimore, MD 21231, USA
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| |
Collapse
|
6
|
Sapino S, Peira E, Chirio D, Chindamo G, Guglielmo S, Oliaro-Bosso S, Barbero R, Vercelli C, Re G, Brunella V, Riedo C, Fea AM, Gallarate M. Thermosensitive Nanocomposite Hydrogels for Intravitreal Delivery of Cefuroxime. NANOMATERIALS 2019; 9:nano9101461. [PMID: 31618969 PMCID: PMC6835325 DOI: 10.3390/nano9101461] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/09/2019] [Accepted: 10/11/2019] [Indexed: 12/15/2022]
Abstract
Endophthalmitis is a rare, but serious, intravitreal inflammatory disorder that can arise after cataract surgery. The intracameral injection of 1 mg cefuroxime (CEF) followed by three-times daily antibiotic topical administration for a week is generally recognized as the routine method of prophylaxis after cataract surgery. This procedure is controversial because of both the low efficacy and the low adherence to therapy by elderly patients. A unique slow release antibiotic intravitreal injection could solve these problems. The objective of the present study was to design ophthalmic nanocomposite delivery systems based on in situ gelling formulations that undergo sol-to-gel transition upon change in temperature to prolong the effect of CEF. Oil in water (O/W) microemulsion (µE) and solid lipid nanoparticles (SLN), obtained with an innovative formulation technology called cold microemulsion dilution, were evaluated as ocular drug delivery systems for CEF. Drug entrapment efficiency up to 80% was possible by esterifying CEF with 1-dodecanol to obtain dodecyl-CEF (dCEF). Both dCEF-loaded SLN and µE were then added with Pluronic®F127 (20% w/v) to obtain a nanocomposite hydrogel-based long acting system. The prepared thermosensitive formulations were evaluated for their physical appearance, drug content, gelation temperature, injectability and rheological properties, in vitro release studies and stability studies. Moreover, cell proliferation assays on human retinal pigment epithelial ARPE-19 cells were performed to evaluate the influence of this innovative system on the cellular viability. In addition, minimal inhibitory concentration (MIC) was assessed for both CEF and dCEF, revealing the need of dCEF hydrolysis for the antimicrobial activity. Although further experimental investigations are required, the physico-chemical characterization of the nanocomposite hydrogels and the preliminary in vitro release studies highlighted the potential of these systems for the sustained release of CEF.
Collapse
Affiliation(s)
- Simona Sapino
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy.
| | - Elena Peira
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy.
| | - Daniela Chirio
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy.
| | - Giulia Chindamo
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy.
| | - Stefano Guglielmo
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy.
| | | | - Raffaella Barbero
- SC of Serology, Istituto Zooprofilattico Sperimentale Piemonte Liguria e Valle d'Aosta, 10154 Turin, Italy.
| | - Cristina Vercelli
- Department of Veterinary Sciences of Turin, University of Turin, 10095 Turin, Italy.
| | - Giovanni Re
- Department of Veterinary Sciences of Turin, University of Turin, 10095 Turin, Italy.
| | | | - Chiara Riedo
- Department of Chemistry, University of Turin, 10125 Turin, Italy.
| | - Antonio Maria Fea
- Department of Surgical Sciences, University of Turin, 10126 Turin, Italy.
| | - Marina Gallarate
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy.
| |
Collapse
|
7
|
Romano MR, Stocchino A, Ferrara M, Lagazzo A, Repetto R. Fluidics of Single and Double Blade Guillotine Vitrectomy Probes in Balanced Salt Solution and Artificial Vitreous. Transl Vis Sci Technol 2018; 7:19. [PMID: 30564508 PMCID: PMC6284468 DOI: 10.1167/tvst.7.6.19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 09/27/2018] [Indexed: 11/29/2022] Open
Abstract
PURPOSE To assess the fluidics of double-vitreous cutter blade (DB) compared with single-blade (SB) guillotine with 23-, 25-, and 27-gauge vitrectomy probes. To assess flow characteristics and flow rates in viscous and viscoelastic fluids. METHODS We used Particle Image Velocimetry to measure the flow field close to the tip of each cutter probe and we derived kinematic quantities of interest, such as kinetic energy and acceleration. We performed measurements both on a balanced salt solution (BSS) and on a viscoelastic artificial vitreous (AV). RESULTS The flow rate is significantly higher with DB than SB vitrectomy probes, for a given pumping pressure and cutting rate. The fluid flow observed is very different between BSS and AV tests. CONCLUSIONS The DB has more efficient fluidics than SB vitrectomy probe in all tested conditions. Fluid acceleration depends on the cutting frequency, especially in the case of measurements in AV. The flow rate strongly depends on the pressure and it is little affected by the cutting frequency, in a range of clinical interest. The 27-G DB produces flow rates similar to the 23- and 25-G SB, with significantly smaller acceleration. The flow induced in the AV is different from that in BSS and oscillates at different frequencies. TRANSLATIONAL RELEVANCE DB cutters prove to be more efficient in terms of lower acceleration for a given flow rate. The latter is mainly controlled by aspiration pressure and less by cut rates. The influence of vitreous rheology deserves further investigations.
Collapse
Affiliation(s)
- Mario Rosario Romano
- Department of Biomedical Sciences, Humanitas University, Rozzano - Milano, Italy
| | - Alessandro Stocchino
- Department of Civil, Chemical and Environmental Engineering, University of Genoa DICCA, Genoa, Italy
| | - Mariantonia Ferrara
- Department of Biomedical Sciences, Humanitas University, Rozzano - Milano, Italy
| | - Alberto Lagazzo
- Department of Civil, Chemical and Environmental Engineering, University of Genoa DICCA, Genoa, Italy
| | - Rodolfo Repetto
- Department of Civil, Chemical and Environmental Engineering, University of Genoa DICCA, Genoa, Italy
| |
Collapse
|
8
|
Two-Dimensional Cutting (TDC) Vitrectome: In Vitro Flow Assessment and Prospective Clinical Study Evaluating Core Vitrectomy Efficiency versus Standard Vitrectome. J Ophthalmol 2016; 2016:3849316. [PMID: 27190635 PMCID: PMC4844880 DOI: 10.1155/2016/3849316] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 03/31/2016] [Indexed: 11/17/2022] Open
Abstract
Purpose. To evaluate comparative aspiration flow performance and also vitrectomy operating time efficiency using a double-cutting open port vitreous cutting system incorporated in a two-dimensional cutting (TDC, DORC International) vitrectome design versus standard vitreous cutter. Methods. In vitro investigations compared aspiration flow rates in artificial vitreous humor at varying cutter speeds and vacuum levels using a TDC vitrectome and a standard vitrectome across different aspiration pump systems. A prospective single-centre clinical study evaluated duration of core vitrectomy in 80 patients with macular pucker undergoing 25-gauge or 27-gauge vitrectomy using either a TDC vitrectome at 16,000 cuts per minute (cpm) or standard single-cut vitrectome, combined with a Valve Timing intelligence (VTi) pump system (EVA, DORC International). Results. Aspiration flow rates remained constant independent of TDC vitrectome cut rate, while flow rates decreased linearly at higher cutter speeds using a classic single-blade vitrectome. Mean duration of core vitrectomy surgeries using a TDC vitreous cutter system was significantly (p < 0.001) shorter than the mean duration of core vitrectomy procedures using a single-cut vitrectome of the same diameter (reduction range, 34%–50%). Conclusion. Vitrectomy surgery performed using a TDC vitrectome was faster than core vitrectomy utilizing a standard single-action vitrectome at similar cut speeds.
Collapse
|
9
|
Bonfiglio A, Lagazzo A, Repetto R, Stocchino A. An experimental model of vitreous motion induced by eye rotations. EYE AND VISION (LONDON, ENGLAND) 2015; 2:10. [PMID: 26613091 PMCID: PMC4660830 DOI: 10.1186/s40662-015-0020-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 04/30/2015] [Indexed: 11/10/2022]
Abstract
BACKGROUND During eye rotations the vitreous humour moves with respect to the eye globe. This relative motion has been suggested to possibly have an important role in inducing degradation of the gel structure, which might lead to vitreous liquefaction and/or posterior vitreous detachment. Aim of the present work is to study the characteristics of vitreous motion induced by eye rotations. METHODS We use an experimental setup, consisting of a Perspex model of the vitreous chamber that, for simplicity, is taken to have a spherical shape. The model is filled with an artificial vitreous humour, prepared as a solution of agar powder and hyaluronic acid sodium salt in deionised water, which has viscoelastic mechanical properties similar to those of the real vitreous. The model rotates about an axis passing through the centre of the sphere and velocity measurements are taken on the equatorial plane orthogonal to the axis of rotation, using an optical technique. RESULTS The results show that fluid viscoelasticity has a strong influence on flow characteristics. In particular, at certain frequencies of oscillation of the eye model, fluid motion can be resonantly excited. This means that fluid velocity within the domain can be significantly larger than that of the wall. CONCLUSIONS The frequencies for which resonant excitation occurs are within the range of possible eye rotations frequencies. Therefore, the present results suggest that resonant excitation of vitreous motion is likely to occur in practice. This, in turn, implies that eye rotations produce large stresses on the retina and within the vitreous that may contribute to the disruption of the vitreous gel structure. The present results also have implications for the choice of the ideal properties for vitreous substitute fluids.
Collapse
Affiliation(s)
- Andrea Bonfiglio
- Department of Civil, Chemical and Environmental Engineering, University of Genoa, Italy, Via Montallegro 1, Genoa, 16145 Italy
| | - Alberto Lagazzo
- Department of Civil, Chemical and Environmental Engineering, University of Genoa, Italy, Via Montallegro 1, Genoa, 16145 Italy
| | - Rodolfo Repetto
- Department of Civil, Chemical and Environmental Engineering, University of Genoa, Italy, Via Montallegro 1, Genoa, 16145 Italy
| | - Alessandro Stocchino
- Department of Civil, Chemical and Environmental Engineering, University of Genoa, Italy, Via Montallegro 1, Genoa, 16145 Italy
| |
Collapse
|
10
|
BAČÁKOVÁ L, NOVOTNÁ K, PAŘÍZEK M. Polysaccharides as Cell Carriers for Tissue Engineering: the Use of Cellulose in Vascular Wall Reconstruction. Physiol Res 2014; 63:S29-47. [DOI: 10.33549/physiolres.932644] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Polysaccharides are long carbohydrate molecules of monosaccharide units joined together by glycosidic bonds. These biological polymers have emerged as promising materials for tissue engineering due to their biocompatibility, mostly good availability and tailorable properties. This complex group of biomolecules can be classified using several criteria, such as chemical composition (homo- and heteropolysaccharides), structure (linear and branched), function in the organism (structural, storage and secreted polysaccharides), or source (animals, plants, microorganisms). Polysaccharides most widely used in tissue engineering include starch, cellulose, chitosan, pectins, alginate, agar, dextran, pullulan, gellan, xanthan and glycosaminoglycans. Polysaccharides have been applied for engineering and regeneration of practically all tissues, though mostly at the experimental level. Polysaccharides have been tested for engineering of blood vessels, myocardium, heart valves, bone, articular and tracheal cartilage, intervertebral discs, menisci, skin, liver, skeletal muscle, neural tissue, urinary bladder, and also for encapsulation and delivery of pancreatic islets and ovarian follicles. For these purposes, polysaccharides have been applied in various forms, such as injectable hydrogels or porous and fibrous scaffolds, and often in combination with other natural or synthetic polymers or inorganic nanoparticles. The immune response evoked by polysaccharides is usually mild, and can be reduced by purifying the material or by choosing appropriate crosslinking agents.
Collapse
Affiliation(s)
- L. BAČÁKOVÁ
- Department of Biomaterials and Tissue Engineering, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | | | | |
Collapse
|
11
|
Lo YK, Chen K, Gad P, Liu W. A fully-integrated high-compliance voltage SoC for epi-retinal and neural prostheses. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2013; 7:761-772. [PMID: 24473541 DOI: 10.1109/tbcas.2013.2297695] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This paper presents a fully functionally integrated 1024-channel mixed-mode and mixed-voltage system-on-a-chip (SoC) for epi-retinal and neural prostheses. Taking an AC input, an integrated power telemetry circuits is capable of generating multiple DC voltages with a voltage conversion efficiency of 83% at a load of 100 mW without external diodes or separate power integrated circuits, reducing the form factor of the prosthetic device. A wireless DPSK receiver with a novel noise reduction scheme supports a data rate of 2 Mb/s at a bit-error-rate of 2 ×10⁻⁷. The 1024-channel stimulator array meets an output compliance voltage of ±10 V and provides flexible stimulation waveforms. Through chip-clustering, the stimulator array can be further expanded to 4096 channels. This SoC is designed and fabricated in TSMC 0.18 μm high-voltage 32 V CMOS process and occupies a chip area of 5.7 mm × 6.6 mm. Using this SoC, a retinal implant bench-top test system is set up with real-time visual verification. In-vitro experiment conducted in artificial vitreous humor is designed and set-up to investigate stimulation waveforms for better visual resolution. In our in-vivo experiment, a hind-limb paralyzed rat with spinal cord transection and implanted chronic epidural electrodes has been shown to regain stepping and standing abilities using stimulus provided by the SoC.
Collapse
|
12
|
Pokki J, Ergeneman O, Bergeles C, Torun H, Nelson BJ. Localized viscoelasticity measurements with untethered intravitreal microrobots. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:2813-6. [PMID: 23366510 DOI: 10.1109/embc.2012.6346549] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Microrobots are a promising tool for medical interventions and micromanipulation. In this paper, we explore the concept of using microrobots for microrheology. Untethered magnetically actuated microrobots were used to characterize one of the most complex biofluids, the vitreous humor. In this work we began by experimentally characterizing the viscoelastic properties of an artificial vitreous humor. For comparison, its properties were also measured using special microcantilevers in an atomic force microscope (AFM) setup. Subsequently, an untethered device was used to study the vitreous humor of a porcine eye, which is a valid ex-vivo model of a human eye. Its viscoelasticity model was extracted, which was in agreement with the model of the artificial vitreous. The existing characterization methodology requires eye and vitreous humor dissection for the microrheology measurements. We envision that the method proposed here can be used in in vivo.
Collapse
Affiliation(s)
- Juho Pokki
- Institute of Robotics and Intelligent Systems, ETH Zurich, 8092 Zurich, Switzerland. jpokki at ethz.ch
| | | | | | | | | |
Collapse
|
13
|
Bergeles C, Kummer MP, Kratochvil BE, Framme C, Nelson BJ. Steerable Intravitreal Inserts for Drug Delivery: In Vitro and Ex Vivo Mobility Experiments. LECTURE NOTES IN COMPUTER SCIENCE 2011; 14:33-40. [DOI: 10.1007/978-3-642-23623-5_5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
|
14
|
Kandagor V, Cela CJ, Sanders CA, Greenbaum E, Lazzi G, Humayun MS, Zhou DM, Castro R, Gaikwad S, Little J. Spatial characterization of electric potentials generated by pulsed microelectrode arrays. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2010:6243-6246. [PMID: 21097346 DOI: 10.1109/iembs.2010.5628058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This presentation is a report on the in situ characterization of stimulating microelectrodes in the context of multielectrode retinal prosthetic implants. The experimental system approximately replicates the geometric and electrical parameters of Second Sight Medical Products' Argus II Retinal Implant. Topographic maps of electric potentials have been prepared for a 60 electrode structure in which selected electrodes were stimulated with biphasic repetitively pulsed charge densities at 100 microC·cm(-2). Surface contour maps were prepared using a 10 microm diameter recording electrode.
Collapse
Affiliation(s)
- V Kandagor
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
In Situ Characterization of Stimulating Microelectrode Arrays: Study of an Idealized Structure Based on Argus II Retinal implants. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/978-0-387-98120-8_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|