Development of an In Situ Printing System With Human Platelet Lysate-Based Bio-Adhesive to Treat Corneal Perforations

Clinical manifestation and management of severe blepharokeratoconjunctivitis combined with corneal perforation

AIM

To investigate the clinical signs of blepharokeratoconjunctivitis (BKC) and evaluate the efficacy of penetrating keratoplasty (PKP) for the disease.

METHODS

Sixteen patients (16 eyes) with BKC complicated by corneal perforation hospitalised at Shandong Eye Hospital were retrospectively analyzed. All patients received PKP. Participants were assessed for symptoms, clinical manifestations, the activity and damage grading of BKC. A paired t-test was used to compare the uncorrected visual acuity (UCVA) before and after surgery for the perforated eye.

RESULTS

The mean age of the patients was 16.3y. Blurred vision is the most common discomfort, followed by redness, and then photophobia. The duration of ocular discomfort lasted for 3.2y, on average. Three (18.8%) participants were associated with rosacea, while 11 (68.8%) patients had recurrent chalazion or hordeolum. Demodex in eyelash follicles was positive in 11 (68.8%) cases. All corneal perforations were ≤3.0 mm in diameter. The perforation was located mainly in the inferior cornea (68.8%). The mean area of corneal vascularisation was 3.0 quadrants. All patients manifested bilateral BKC, with the perforated eyes ranked as severely damaged and presenting with severe inflammation. Most contralateral eyes manifested mild damage with no active inflammation. Majority (68.8%) of the perforated eyes were treated with PKP using a minimal graft. The UCVA increased significantly at the final follow-up (mean, 21mo; P<0.001), with the manifestation of BKC alleviated greatly. None of the patients developed immune rejection or other serious complications.

CONCLUSION

BKC combined with corneal perforation occurs mainly among young people with a long history of ocular discomfort. PKP, especially using a minimal graft, is an effective and safe option for treating the disease.

Adhesion Mechanism, Applications, and Challenges of Ocular Tissue Adhesives

Corneal injury is prevalent in ophthalmology, with mild cases impacting vision and severe cases potentially resulting in permanent blindness. In clinical practice, standard treatments for corneal injury involve transplantation surgery combined with pharmacological therapy. However, surgical sutures exhibit several limitations, which can be overcome using tissue adhesives. With recent advances in biomedical materials, the use of ophthalmic tissue adhesives has expanded beyond wound closure, including tissue filling and drug delivery. Furthermore, the use of tissue adhesives has demonstrated promising outcomes in drug delivery, ophthalmic disease diagnosis, and biological scaffolds. This study briefly introduces common adhesion mechanisms and their applications in ophthalmology, aiming to increase interest in tissue adhesives and clinical ophthalmic treatment.

Simultaneous processing of both handheld biomixing and biowriting of kombucha cultured pre-crosslinked nanocellulose bioink for regeneration of irregular and multi-layered tissue defects

The nanocellulosic pellicle derived from the symbiotic culture of bacteria and yeast (Kombucha SCOBY) is an important biomaterial for 3D bioprinting in tissue engineering. However, this nanocellulosic hydrogel has a highly entangled gel network. This needs to be partially modified to improve its processability and extrusion ability for its applications in the 3D bioprinting area. To control its mechanical and biological properties for direct 3D bioprinting applications, uniform reinforcement of nanocellulose-interacting polymers and nanoparticles in such a prefabricated gel network is essential. In this study, the hydrogel network is partially hydrolyzed with organic acid and subsequently transformed into a 3D bioprintable polyelectrolyte complex with chitosan and kaolin nanoparticles without any chemical crosslinker using a handheld 3D bioprinter. This handheld bioprinter ensures homogeneity in both biomixing and bioprinting of chitosan and kaolin within the modified nanocellulose network for multi-layered bioprinted scaffolds through an extensional shear mechanism. The biomixing simulation, mechanical (static, dynamic, and cyclic), 3D bioprinting, and cellular studies confirm the homogeneous biomixing of kaolin nanoparticles and live cells in this nanocellulose-chitosan polyelectrolyte hydrogel. The combination of SCOBY-derived nanocellulose-chitosan bioink with kaolin nanoparticles and a screw-driven handheld extrusion bioprinter demonstrates a promising platform for layer-by-layer regeneration of complex tissues with homogeneous cell/particle distribution with high cell viability.

Revisiting the Use of Deep Temporalis Fascia Grafts in Ophthalmology

PURPOSE

To report new indications for deep temporalis fascia (DTF) grafts in the ophthalmic field.

METHODS

Monocentric retrospective interventional case series study. All the patients who underwent a DTF graft in an unpublished new indication over the study period (May 2020-October 2023) were included. For each patient, gender, age, graft indication, outcomes, complications, and follow-up duration were collected. In most cases, the DTF graft was covered by a vascularized flap.

RESULTS

Eight patients underwent a DTF graft over the study period. The indications were: radiotherapy-induced scleral necrosis in three cases, tendinoplasty to replace the inferior rectus muscle tendon invaded by a locally advanced conjunctival carcinoma in one case, Ahmed glaucoma valve tube exposure in one case, intraocular lens with scleral fixation exposure in one case, orbital cerebrospinal fluid fistula (orbitorrhea) in one case, and post-traumatic complete corneal graft loss in one case. The DTF graft was successful in 87.5% of cases after a mean follow-up of 11.4 months. No complications were observed.

CONCLUSIONS

DTF graft is a highly versatile graft that can be easily harvested. New indications for DTF grafts may include the repair of radiotherapy-induced scleral necrosis, the creation of oculomotor tendon and the temporary packing of large ocular tissue loss in an emergency context. Further studies with a longer follow-up are needed to confirm our preliminary results.

3D printing of biologics-what has been accomplished to date?

Three-dimensional (3D) printing is a promising approach for the stabilization and delivery of non-living biologics. This versatile tool builds complex structures and customized resolutions, and has significant potential in various industries, especially pharmaceutics and biopharmaceutics. Biologics have become increasingly prevalent in the field of medicine due to their diverse applications and benefits. Stability is the main attribute that must be achieved during the development of biologic formulations. 3D printing could help to stabilize biologics by entrapment, support binding, or crosslinking. Furthermore, gene fragments could be transited into cells during co-printing, when the pores on the membrane are enlarged. This review provides: (i) an introduction to 3D printing technologies and biologics, covering genetic elements, therapeutic proteins, antibodies, and bacteriophages; (ii) an overview of the applications of 3D printing of biologics, including regenerative medicine, gene therapy, and personalized treatments; (iii) information on how 3D printing could help to stabilize and deliver biologics; and (iv) discussion on regulations, challenges, and future directions, including microneedle vaccines, novel 3D printing technologies and artificial-intelligence-facilitated research and product development. Overall, the 3D printing of biologics holds great promise for enhancing human health by providing extended longevity and enhanced quality of life, making it an exciting area in the rapidly evolving field of biomedicine.

3D bioprinting of complex tissue scaffolds with in situ homogeneously mixed alginate-chitosan-kaolin bioink using advanced portable biopen

Control of in situ 3D bioprinting of hydrogel without toxic crosslinker is ideal for tissue regeneration by reinforcing and homogeneously distributing biocompatible reinforcing agent during fabrication of large area and complex tissue engineering scaffolds. In this study, homogeneous mixing, and simultaneous 3D bioprinting of a multicomponent bioink based on alginate (AL)-chitosan (CH), and kaolin was obtained by an advanced pen-type extruder to ensure structural and biological homogeneity during the large area tissue reconstruction. The static, dynamic and cyclic mechanical properties as well as in situ self-standing printability significantly improved with the kaolin concentration for AL-CH bioink-printed samples due to polymer-kaolin nanoclay hydrogen bonding and cross-linking with less amount of calcium ions. The Biowork pen ensures better mixing effectiveness for the kaolin-dispersed AL-CH hydrogels (evident from computational fluid dynamics study, aluminosilicate nanoclay mapping and 3D printing of complex multilayered structures) than the conventional mixing process. Two different cell lines (osteoblast and fibroblast) introduced during large area multilayered 3D bioprinting have confirmed the suitability of such multicomponent bioinks for in vitro even tissue regeneration. The effect of kaolin to promote uniform growth and proliferation of the cells throughout the bioprinted gel matrix is more significant for this advanced pen-type extruder processed samples.