A novel suprachoroidal microinvasive glaucoma implant: in vivo biocompatibility and biointegration

Clinical Results of the MINIject Implant for Suprachoroidal Drainage

Objective: This retrospective study evaluated the safety and efficacy of the new minimally invasive MINIject implant placed in the suprachoroidal space. The aim was to assess its impact on intraocular pressure (IOP) reduction and complication rate. Methods: 18 eyes from 18 patients with insufficiently controlled glaucoma received the implant using topical medications. Outcomes were changes in IOP, change in IOP medication, need for other glaucoma surgery, and rate of adverse events. Results: IOP reduced by 15% (p < 0.05) following MINIject implantation. IOP medication decreased from 3 to 1 agent (p < 0.05). Four patients (22%) required other glaucoma surgery while we did not observe any clinically relevant adverse event. Conclusions: This retrospective study indicates that MINIject implants may be a safe and effective means of reducing IOP together with a reduction in IOP medications in most patients. Larger prospective studies with longer follow-ups are necessary to confirm our results, though.

Novel Biomaterials in Glaucoma Treatment

Glaucoma is a significant cause of blindness worldwide, and its treatment remains challenging. The disease progressively leads to damage to the optic disc and thus loss of visual acuity and visual field. High intraocular pressure (IOP) is a common risk factor. There are three major methods to treat this disease: topical, laser, and surgical. None of these are completely satisfactory; therefore, alternatives using new biomaterials are being sought. Since biomaterial engineering has experienced significant growth in recent decades, its products are gradually being introduced to various branches of medicine, with the exception of ophthalmology. Biomaterials, such as glaucoma drainage implants, have been successfully used to treat glaucoma. There is significant ongoing research on biomaterials as drug delivery systems that could overcome the disadvantages of topical glaucoma treatment, such as poor intraocular penetration or frequent drug administration. This article summarizes the use of novel biomaterials for glaucoma treatment presented in the literature. The literature search was based on articles published in English on PubMed.gov, Cochranelibrary.com, and Scopus.com between 2018 and 2023 using the following term "biomaterials in glaucoma." A total of 103 published articles, including twenty-two reviews, were included. Fifty-nine articles were excluded on the basis of their titles and abstracts.

Two-Year Performance and Safety Results of the MINIject Supraciliary Implant in Patients With Primary Open-Angle Glaucoma: Meta-Analysis of the STAR-I, II, III Trials

PURPOSE

To evaluate the performance and safety of minimally invasive glaucoma surgery with a supraciliary drainage device (MINIject; iSTAR Medical, Wavre, Belgium) in primary open-angle glaucoma (POAG) as a stand-alone procedure.

DESIGN

Meta-analysis.

METHODS

At 11 sites in Colombia, France, Germany, India, Panama, and Spain, 82 patients were treated in 3 prospective, multicenter, interventional, nonrandomized trials (STAR-I, II, III). Data were pooled in a meta-analysis of up to 2 years of follow-up postimplantation. The main outcome measures were mean relative and absolute reduction in diurnal intraocular pressure (IOP) compared to baseline. Secondary outcomes included patients with IOP ≤18 mmHg, patients with IOP reduction ≥20%, number of IOP-lowering medications, adverse events, and endothelial cell density loss.

RESULTS

At the 2-year follow-up (n = 66), mean IOP was reduced from 23.8 ± 3.3 mmHg at baseline to 14.4 ± 4.5 mmHg (-39.3%; P < 0.0001). An IOP reduction of ≥20% was achieved in 89.4% of patients, with 84.8% having an IOP ≤18 mmHg. IOP-lowering medications were reduced from a mean of 2.4 ± 1.1 to 1.4 ± 1.4 (P < 0.0001), with 37.9% of patients being medication-free at 2 years. Mean endothelial cell density loss at 2 years was 6.2 ± 9.1% compared to baseline and no patient had a loss >30%.

CONCLUSIONS

This meta-analysis demonstrates the favorable safety and efficacy profile of a supraciliary device implanted in a stand-alone, ab-interno procedure in patients with mild-to-moderate POAG. The data demonstrate that MINIject is a safe and effective, bleb-free treatment option for patients requiring low target IOP up to 2 years.

In vivo evaluation of a nanotechnology-based microshunt for filtering glaucoma surgery

To carry out the preclinical and histological evaluation of a novel nanotechnology-based microshunt for drainage glaucoma surgery. Twelve New Zealand White rabbits were implanted with a novel microshunt and followed up for 6 weeks. The new material composite consists of the silicone polydimethylsiloxane (PDMS) and tetrapodal Zinc Oxide (ZnO-T) nano-/microparticles. The microshunts were inserted ab externo to connect the subconjunctival space with the anterior chamber. Animals were euthanized after 2 and 6 weeks for histological evaluation. Ocular health and implant position were assessed at postoperative days 1, 3, 7 and twice a week thereafter by slit lamp biomicroscopy. Intraocular pressure (IOP) was measured using rebound tonometry. A good tolerability was observed in both short- and medium-term follow-up. Intraocular pressure was reduced following surgery but increased to preoperative levels after 2 weeks. No clinical or histological signs of inflammatory or toxic reactions were seen; the fibrotic encapsulation was barely noticeable after two weeks and very mild after six weeks. The new material composite PDMS/ZnO-T is well tolerated and the associated foreign body fibrotic reaction quite mild. The new microshunt reduces the IOP for 2 weeks. Further research will elucidate a tube-like shape to improve and prolong outflow performance and longer follow-up to exclude medium-term adverse effects.

Biotissue stent for supraciliary outflow in open-angle glaucoma patients: surgical procedure and first clinical results of an aqueous drainage biostent

BACKGROUND/AIMS

To report a first-in-human trial in open-angle glaucoma (OAG) subjects treated with a new microinterventional biostent-reinforced cyclodialysis technique to enhance supraciliary aqueous drainage.

METHODS

Subjects (N=10; 74.1±7.9 years old) with OAG and cataracts underwent combined phacoemulsification cataract surgery with implantation of a permanent endoscleral supraciliary biostent to reinforce a controlled cyclodialysis cleft. The biostent comprised decellularised scleral allograft tissue microtrephined into a polymer tubular implant intraoperative/postoperative safety, intraocular pressure (IOP) and glaucoma medications were tracked through 12 months postimplantation.

RESULTS

Baseline medicated IOP averaged 24.2±6.9 mm Hg with subjects using 1.3±0.8 IOP-lowering medications. Successful biostent implantation was achieved in all individuals without significant complications. Immediate IOP lowering was sustained through 1 year. Twelve-month mean IOP was reduced 40% from baseline to 14.6±3.2 mm Hg (p=0.004; paired two-tailed t-test), and 80% of patients achieved >20% IOP reduction. Biostenting reduced glaucoma medication use 62%, from a baseline mean of 1.3 required medications to 0.5 medications (p=0.037) at postoperative 12 months. The biotissue implant was well tolerated and demonstrated good endothelial safety with only 11% endothelial cell loss at 12 months after combined phaco-biostenting surgery, similar to that expected after phacoemulsification alone. Mean BCVA increased from baseline 20/130 Snellen to 20/36 at postoperative 12 months (p=0.001).

CONCLUSION

Supraciliary biostenting in OAG patients is well tolerated, has a good safety profile and produces long-term IOP-lowering while reducing glaucoma medication requirements.

Minimally Invasive Glaucoma Surgery: Latest Developments and Future Challenges

The development of minimally invasive glaucoma surgeries (MIGSs) was intended to provide safe and modestly efficacious modalities for early intervention of mild-to-moderate glaucoma, with minimal trauma and rapid recovery. They were mainly ab interno procedures that reduce intraocular pressure by facilitating the aqueous outflow by bypassing the trabecular meshwork resistance, reinforcing the uveoscleral flow via the supraciliary space, and reducing aqueous production by the ciliary body. While the cumulating evidence helps shape the role of the available MIGS, the exponential new development and advancement in this field has expanded the territory of MIGS. Apart from developing subconjunctival MIGS filtration devices (Xen gel stent and PRESERFLO MicroShunt), there is a tendency to revisit the "traditional" MIGS for alternative use and to modify the procedures with consideration of the fundamental aqueous outflow physiology. Combined MIGS has also been suggested, based on the theory that their different mechanisms may provide additive or synergistic effects. The advancement of laser procedures is also promising and could supplement unmet needs along the glaucoma treatment algorithm. This review examines the broad array of MIGS, updates the recent findings, discusses their potential alternative applications, and explores future challenges.

New Devices in Glaucoma

Glaucoma remains a leading cause of blindness globally. Minimally invasive treatment techniques are rapidly expanding the availability of therapeutic options for glaucoma. These include devices aimed at enhancing outflow through the subconjunctival space, Schlemm's canal, and suprachoroidal space, sustained-release drug delivery devices, and extraocular devices aiming to reduce glaucomatous progression through other novel means. In this review, we provide an overview of several novel devices either newly available or in development for the medical and surgical management of glaucoma. Further studies are required to determine the long-term efficacy of these devices and how they will integrate into the current landscape of glaucoma management.

Clinical and Optical Coherence Tomography Evidence of Aqueous Humor Flow from the Suprachoroidal Space to Conjunctival Lymphatics

A surgical technique was developed to enhance aqueous humor (AH) flow through the non-trabecular outflow pathway by rerouting it from the anterior chamber (AC) to the suprachoroidal space (SCS) without detaching the ciliary body from the scleral spur. Medium- and long-term surgical outcomes were retrospectively analyzed in a case series of 58 glaucoma patients. At 6, 12, and 24 months, the mean IOP decreased from 27.8 ± 8.3 to 14.9 ± 5.0 mmHg, median 15.0 (25th percentile (p25)13.0; 75th percentile (p75) 18.0) and 15.2 ± 3.3 mmHg, and hypotensive medication use reduced from a median (p25; p75) of 3 (2; 3) to 0 (0; 2), 0 (0; 2), and 0 (0; 1.5), respectively. Intra- and postoperative complications were few and manageable. Following surgery, no bleb formation occurred in any of the cases (as confirmed by optical coherence tomography). Conjunctival lymphatic vessels (CLVs) developed in 50% of eyes (29/58). Clinically, they developed directly from sclera and had no connection to the surgical site. Analysis further showed that the development of CLVs and their longer visibility period had poor prognostic value for IOP control. If the fluid flow from the SCS to CLVs was resistance-free, no CLV development was evident. However, if any resistance existed in the flow, the fluid accumulated in lymphatics, resulting in their engorgement. The proposed technique was safe and effective in decreasing IOP in glaucoma patients by enhancing AH flow from the SCS to CLVs via connecting intrascleral microchannels.

Surgical Augmentation of the Suprachoroidal Space: A Novel Material and Implant

Microinvasive glaucoma surgery (MIGS) has emerged as a safer method to lower IOP with minimal impact on patient quality of life compared to traditional glaucoma surgeries. With the advent of MIGS, there has been a renewed interest in exploring the suprachoroidal route. MIGS targeting the suprachoroidal space allow for a safe reduction in IOP while sparing conjunctiva and allowing "blebless" surgery, thus avoiding bleb-related complications. This article aims to review the rationale behind the suprachoroidal MIGS procedures and the literature surrounding the efficacy and safety of a novel suprachoroidal device, the MINIject. The available literature has shown promising IOP lowering results with the MINIject implant with a potentially safer and less invasive approach than traditional glaucoma surgeries.

Development of an in-situ forming, self-healing scaffold for dermal wound healing: in-vitro and in-vivo studies

The importance of the extra-cellular matrix (ECM) for wound healing has been extensively researched. Understanding its importance, multiple ECM mimetic scaffolds have been developed. However, the majority of such scaffolds are prefabricated. Due to their stiffness, prefabricated scaffolds cannot come into direct contact with the basal skin cells at the wound bed, limiting their efficacy. We have developed a unique wound dressing, using chitosan (CH) and chondroitin sulfate (CS), that can form a porous scaffold (CH-CS PEC) in-situ, at the wound site, by simple mixing of the polymer solutions. As CH is positively and CS is negatively charged, mixing these two polymer solutions would lead to electrostatic cross-linking between the polymers, converting them to a porous, viscoelastic scaffold. Owing to the in-situ formation, the scaffold can come in direct contact with the cells at the wound bed, supporting their proliferation and biofunction. In the present study, we confirmed the cross-linked scaffold formation by solid-state NMR, XRD, and TGA analysis. We have demonstrated that the scaffold had a high viscoelastic property, with self-healing capability. Both keratinocyte and fibroblast cells exhibited significantly increased migration and functional markers expression when grown on this scaffold. In the rat skin-excisional wound model, treatment with the in-situ forming CH-CS PEC exhibited enhanced wound healing efficacy. Altogether, this study demonstrated that mixing CH and CS solutions lead to the spontaneous formation of a highly viscoelastic, porous scaffold, which can support epidermal and dermal cell proliferation and bio-function, with an enhanced in-vivo wound healing efficacy.

Electro-conductive carbon nanofibers containing ferrous sulfate for bone tissue engineering

The application of electroactive scaffolds can be promising for bone tissue engineering applications. In the current paper, we aimed to fabricate an electro-conductive scaffold based on carbon nanofibers (CNFs) containing ferrous sulfate. FeSO₄·7H₂O salt with different concentrations 5, 10, and 15 wt%, were blended with polyacrylonitrile (PAN) polymer as the precursor and converted to Fe₂O3/CNFs nanocomposite by electrospinning and heat treatment. The characterization was conducted using SEM, EDX, XRD, FTIR, and Raman methods. The results showed that the incorporation of Fe salt induces no adverse effect on the nanofibers' morphology. EDX analysis confirmed that the Fe ions are uniformly dispersed throughout the CNF mat. FTIR spectroscopy showed the interaction of Fe salt with PAN polymer. Raman spectroscopy showed that the incorporation of FeSO4·7H₂O reduced the ID/IG ratio, indicating more ordered carbon in the synthesized nanocomposite. Electrical resistance measurement depicted that, although the incorporation of ferrous sulfate reduced the electrical conductivity, the conductive is suitable for electrical stimulation. The in vitro studies revealed that the prepared nanocomposites were cytocompatible and only negligible toxicity (less than 10%) induced by CNFs/Fe₂O₃ fabricated from PAN FeSO₄·7H₂O 15%. Although various nanofibrous composite fabricated with Fe NPs have been evaluated for tissue engineering applications, CNFs exhibited promising properties, such as excellent mechanical strength, biocompatibility, and electrical conductivity. These results showed that the fabricated nanocomposites could be applied as the bone tissue engineering scaffold.

Poly-ε-caprolactone/Whitlockite Electrospun Bionic Membrane with an Osteogenic-Angiogenic Coupling Effect for Periosteal Regeneration

The periosteum is rich in vascular networks, osteoprogenitor cells, and stem cells and plays an important role in bone defect repair. However, existing artificial periosteum materials still have difficulty in meeting clinical requirements, such as good mechanical properties and bionic structure construction, osteogenic differentiation, and vascularization capabilities. Here, a poly-ε-caprolactone (PCL)/whitlockite (WH, 5, 10, 15 wt %) artificial periosteum with different doping amounts was prepared by electrospinning technology. According to the results of in vitro mineralization experiments, the rapid ion release from WH promotes the deposition of mineralized hydroxyapatite. Inductively coupled plasma-optical emission spectroscopy, in vitro angiogenesis, and cell migration experiments showed that the bionic periosteum of the 15% WH group had the best release rate of Mg²⁺ and the best ability to promote the human umbilical vein endothelial cell angiogenesis and migration. In addition, this group promoted collagen formation and calcium deposition. Finally, the subcutaneous implantation model was used to verify the biocompatibility and angiogenesis ability of the proposed membrane in vivo. Overall, this biomimetic PCL/WH nanofiber membrane combines the positive osteogenic differentiation ability and angiogenic ability of calcium phosphate materials and thus has good application prospects in the field of periosteal repair in the future.

Core-shell PLA/Kef hybrid scaffolds for skin tissue engineering applications prepared by direct kefiran coating on PLA electrospun fibers optimized via air-plasma treatment

Over the recent years, there is a growing interest in electrospun hybrid scaffolds composed of synthetic and natural polymers that can support cell attachment and proliferation. In this work, the physical and biological properties of polylactic acid (PLA) electrospun mats coated with kefiran (Kef) were evaluated. Gravimetric, spectroscopic (FTIR-ATR) and morphological investigations via scanning electron microscopy confirmed the effective formation of a thin kefiran layer wrapped on the PLA fibers with an easy-tunable thickness. Air plasma pre-treatment carried out on PLA (P-PLA) affected both the morphology and the crystallinity of Kef coating as confirmed by differential scanning calorimetry and X-ray diffraction analyses. Scaffolds were mechanically characterized with tensile tests to evaluate the reinforcing action of the Kef coating. The water resistance of Kefiran coating in distilled water at 37 °C evaluated on both PLA/Kef and P-PLA/Kef was carried out by gravimetric and morphological analyses. Finally, cell culture assays with embryonic fibroblast cells were conducted on selected hybrid scaffolds to compare the cell proliferation, morphology, and collagen production with PLA and P-PLA electrospun scaffolds. Based on the results, we can demonstrate that direct coating of PLA from Kef/water solutions is an effective approach to prepare hybrid scaffolds with tunable properties and that the plasma pre-treatment enhances the affinity between PLA and Kefiran. In vitro tests demonstrated the great potential of PLA/Kef hybrid scaffolds for skin tissue engineering.

Sustainable Antibacterial Surgical Suture Using a Facile Scalable Silk-Fibroin-Based Berberine Loading System

Medical sutures with sustainable antibacterial properties can effectively inhibit pathogens, thus avoiding the occurrence of surgical site infection and reducing the recurrence of patients resulting in postoperative death. This paper describes a facile scalable antibacterial surgical suture with sustainable antibacterial function and fair mechanical and biocompatible properties using a simple, efficient, and eco-friendly method. Silk filaments were braided into a core-shell structure using a braiding machine, and then silk fibroin (SF) films loaded with different percentages of berberine (BB) were coated onto the surface of the suture. The drug-loaded sutures performed a slow drug-release profile of more than 7 days. Retention of the knot-pull tensile strength of all groups was above 87% during in vitro degradation within 42 days. The sutures had no toxicity to the cells' in vitro cytotoxicity. The results of the in vivo biocompatibility test showed mild inflammation and clear signs of supporting angiogenesis in the implantation site of the rats. This work provides a new route for achieving a BB-loaded and high-performance antibacterial suture, which is of great potential in applications for surgical operations.

Biocompatible hyaluronic acid-divinyl sulfone injectable hydrogels for sustained drug release with enhanced antibacterial properties against Staphylococcus aureus

Hyaluronic acid (HA) solutions were crosslinked with divinyl sulfone (DVS) and subsequently loaded with antibiotic molecules to obtain biocompatible and antibacterial injectable hydrogels. The crosslinking degree of the hydrogels was modulated by varying the reaction time and the HA:DVS weight ratio. Synthesized HA-DVS hydrogels were characterized by their rheological properties, pore size, swelling capacity and hydrolytic and thermal degradation. Biocompatibility was assessed by measuring pH, osmolality and by in vitro cytotoxic assay. Acetyl salicylic (AAS) loaded hydrogels display anti-inflammatory properties in vitro, whereas cefuroxime (CFX), tetracycline (TCN) and amoxicillin (AMX) loaded hydrogels show in vitro antibacterial activity against Staphylococcus aureus. The combine use of antibiotics and AAS produces a synergic effect that reduces the S. aureus population up to a log10 reduction (R) of 5.55. Overall results show that antibiotic/AAS loaded HA-DVS hydrogels could be effectively used to combat S. aureus infections and to increase the antibacterial activity of antibiotics commonly used against S. aureus.