2022

Endothelial keratoplasty (EK), including Descemet stripping endothelial keratoplasty and Descemet membrane endothelial keratoplasty, is now the most performed corneal transplant procedure in the United States. Intraocular pressure (IOP) elevation and glaucoma are common complications and can cause irreversible vision loss and corneal graft failure. This review will cover the incidence, risk factors, and management of glaucoma and IOP elevation after EK. Higher preoperative IOP, preoperative glaucoma, and certain indications for EK, such as bullous keratopathy, are associated with increased risk of glaucoma and glaucoma progression in patients undergoing EK. In addition, we summarize the studies assessing graft outcomes in EK patients with glaucoma or glaucoma surgery. Finally, we provide future directions to improve clinical care in EK patients with glaucoma.

PURPOSE: To assess clinical outcomes of patients with severe, cicatricial ocular surface disease (OSD) implanted with the currently marketed design of the Boston keratoprosthesis type II (BK2). DESIGN: Retrospective cohort study. METHODS: Records of consecutive patients undergoing BK2 implantation from June 2009 to March 2021 were assessed for postoperative visual acuity, postoperative complications, device replacement, and additional surgeries. RESULTS: Fifty-six eyes of 53 patients with a mean follow-up of 45.8 months (range, 0.2-134.7 months) were included. Stevens-Johnson syndrome/toxic epidermal necrolysis was the most common indication (49.1%), followed by mucous membrane pemphigoid (39.6%) and other OSD (11.3%). Visual acuity improved from logMAR 2.2 ± 0.5 preoperatively to 1.5 ± 1.2 at final follow-up. Of 56 eyes, 50 saw ≥20/200 at some point postoperatively. Of the eyes with a follow-up of more than 5 years, 50.0% retained a visual acuity of ≥20/200 at their final follow-up. The most common complications over the entire postoperative course (mean ∼4 years) were de novo or worsening glaucoma (41.1%), choroidal effusions (30.3%), retinal detachment (25.0%), and end-stage glaucoma (25.0%). In a univariate analysis, patients who experienced irreversible loss of ≥20/200 visual acuity were more likely to have been previously implanted with an older design of BK2, less likely to be on preoperative systemic immunosuppressive therapy, and less likely to have undergone concurrent glaucoma tube implantation, compared to patients who retained ≥20/200 acuity (P < .04 for all). CONCLUSIONS: Advances in device design and postoperative care have made implantation of BK2 a viable option for corneal blindness in the setting of severe cicatricial OSD.

PURPOSE OF REVIEW: This review paper aims at discussing pathogenesis, etiology, clinical features, management, and prognosis of OPN. RECENT FINDINGS: Optic perineuritis (OPN) is an inflammatory process primarily involving the optic nerve sheath. Clinically, OPN usually presents with unilateral, gradual decline of visual function, eye pain, and/or pain on eye movements, disc edema and various features of optic nerve dysfunction, including visual field defects. It can mimic typical optic neuritis. In most cases of OPN, the disease is isolated with no specific etiology being identified, however, it can also occur secondary to a wide range of underlying systemic diseases. OPN is clinically diagnosed and radiologically confirmed based on the finding of circumferential perineural enhancement of the optic nerve sheath on magnetic resonance imaging (MRI). SUMMARY: Unlike optic nerve, OPN is not typically self-limited without treatment. High-dose oral corticosteroids are the mainstay of treatment in OPN. The initiation of therapy usually causes rapid and dramatic improvement in signs and symptoms. In general, OPN usually has a relatively good visual prognosis, which is influenced by delays between the onset of visual loss and the initiation of steroid therapy as well as the presence of underlying systemic diseases.

BACKGROUND: Carbapenem-resistant Enterobacterales (CRE) are an urgent global health threat. Inferring the dynamics of local CRE dissemination is currently limited by our inability to confidently trace the spread of resistance determinants to unrelated bacterial hosts. Whole-genome sequence comparison is useful for identifying CRE clonal transmission and outbreaks, but high-frequency horizontal gene transfer (HGT) of carbapenem resistance genes and subsequent genome rearrangement complicate tracing the local persistence and mobilization of these genes across organisms. METHODS: To overcome this limitation, we developed a new approach to identify recent HGT of large, near-identical plasmid segments across species boundaries, which also allowed us to overcome technical challenges with genome assembly. We applied this to complete and near-complete genome assemblies to examine the local spread of CRE in a systematic, prospective collection of all CRE, as well as time- and species-matched carbapenem-susceptible Enterobacterales, isolated from patients from four US hospitals over nearly 5 years. RESULTS: Our CRE collection comprised a diverse range of species, lineages, and carbapenem resistance mechanisms, many of which were encoded on a variety of promiscuous plasmid types. We found and quantified rearrangement, persistence, and repeated transfer of plasmid segments, including those harboring carbapenemases, between organisms over multiple years. Some plasmid segments were found to be strongly associated with specific locales, thus representing geographic signatures that make it possible to trace recent and localized HGT events. Functional analysis of these signatures revealed genes commonly found in plasmids of nosocomial pathogens, such as functions required for plasmid retention and spread, as well survival against a variety of antibiotic and antiseptics common to the hospital environment. CONCLUSIONS: Collectively, the framework we developed provides a clearer, high-resolution picture of the epidemiology of antibiotic resistance importation, spread, and persistence in patients and healthcare networks.

PURPOSE: To compare nonmydriatic (NM) and mydriatic (MD) handheld retinal imaging with standard ETDRS 7-field color fundus photography (ETDRS photographs) for the assessment of diabetic retinopathy (DR) and diabetic macular edema (DME). DESIGN: Prospective, comparative, instrument validation study. SUBJECTS: A total of 225 eyes from 116 patients with diabetes mellitus. METHODS: Following a standardized protocol, NM and MD images were acquired using handheld retinal cameras (NM images: Aurora, Smartscope, and RetinaVue-700; MD images: Aurora, Smartscope, RetinaVue-700, and iNview) and dilated ETDRS photographs. Grading was performed at a centralized reading center using the International Clinical Classification for DR and DME. Kappa statistics (simple [K], weighted [Kw]) assessed the level of agreement for DR and DME. Sensitivity and specificity were calculated for any DR, referable DR (refDR), and vision-threatening DR (vtDR). MAIN OUTCOME MEASURES: Agreement for DR and DME; sensitivity and specificity for any DR, refDR, and vtDR; ungradable rates. RESULTS: Severity by ETDRS photographs: no DR, 33.3%; mild nonproliferative DR, 20.4%; moderate DR, 14.2%; severe DR, 11.6%; proliferative DR, 20.4%; no DME, 68.0%; DME, 9.3%; non-center involving clinically significant DME, 4.9%; center-involving clinically significant DME, 12.4%; and ungradable, 5.3%. For NM handheld retinal imaging, Kw was 0.70 to 0.73 for DR and 0.76 to 0.83 for DME. For MD handheld retinal imaging, Kw was 0.68 to 0.75 for DR and 0.77 to 0.91 for DME. Thresholds for sensitivity (0.80) and specificity (0.95) were met by NM images acquired using Smartscope and MD images acquired using Aurora and RetinaVue-700 cameras for any DR and by MD images acquired using Aurora and RetinaVue-700 cameras for refDR. Thresholds for sensitivity and specificity were met by MD images acquired using Aurora and RetinaVue-700 for DME. Nonmydriatic and MD ungradable rates for DR were 15.1% to 38.3% and 0% to 33.8%, respectively. CONCLUSIONS: Following standardized protocols, NM and MD handheld retinal imaging devices have substantial agreement levels for DR and DME. With mydriasis, not all handheld retinal imaging devices meet standards for sensitivity and specificity in identifying any DR and refDR. None of the handheld devices met the established 95% specificity for vtDR, suggesting that lower referral thresholds should be used if handheld devices must be utilized. When using handheld devices, the ungradable rate is significantly reduced with mydriasis and DME sensitivity thresholds are only achieved following dilation.

A family, with two affected identical twins with early-onset recessive inherited retinal degeneration, was analyzed to determine the underlying genetic cause of pathology. Exome sequencing revealed a rare and previously reported causative variant (c.1923_1969delinsTCTGGG; p.Asn643Glyfs*29) in the PDE6B gene in the affected twins and their unaffected father. Further investigation, using genome sequencing, identified a novel ∼7.5-kb deletion (Chr 4:670,405-677,862del) encompassing the ATP5ME gene, part of the 5' UTR of MYL5, and a 378-bp (Chr 4:670,405-670,782) region from the 3' UTR of PDE6B in the affected twins and their unaffected mother. Both variants segregated with disease in the family. Analysis of the relative expression of PDE6B, in peripheral blood cells, also revealed a significantly lower level of PDE6B transcript in affected siblings compared to a normal control. PDE6B is associated with recessive rod-cone degeneration and autosomal dominant congenital stationary night blindness. Ophthalmic evaluation of these patients showed night blindness, fundus abnormalities, and peripheral vision loss, which are consistent with PDE6B-associated recessive retinal degeneration. These findings suggest that the loss of PDE6B transcript resulting from the compound heterozygous pathogenic variants is the underlying cause of recessive rod-cone degeneration in the study family.

BACKGROUND: Human-induced pluripotent stem cell-derived retinal organoids are a valuable tool for disease modelling and therapeutic development. Many efforts have been made over the last decade to optimise protocols for the generation of organoids that correctly mimic the human retina. Most protocols use common media supplements; however, protocol-dependent variability impacts data interpretation. To date, the lack of a systematic comparison of a given protocol with or without supplements makes it difficult to determine how they influence the differentiation process and morphology of the retinal organoids. METHODS: A 2D-3D differentiation method was used to generate retinal organoids, which were cultured with or without the most commonly used media supplements, notably retinoic acid. Gene expression was assayed using qPCR analysis, protein expression using immunofluorescence studies, ultrastructure using electron microscopy and 3D morphology using confocal and biphoton microscopy of whole organoids. RESULTS: Retinoic acid delayed the initial stages of differentiation by modulating photoreceptor gene expression. At later stages, the presence of retinoic acid led to the generation of mature retinal organoids with a well-structured stratified photoreceptor layer containing a predominant rod population. By contrast, the absence of retinoic acid led to cone-rich organoids with a less organised and non-stratified photoreceptor layer. CONCLUSIONS: This study proves the importance of supplemented media for culturing retinal organoids. More importantly, we demonstrate for the first time that the role of retinoic acid goes beyond inducing a rod cell fate to enhancing the organisation of the photoreceptor layer of the mature organoid.

PURPOSE: To evaluate the surgical success and need for adjustment due to overcorrection in patients who undergo inferior oblique myectomy (IOM) combined with lateral rectus recession (LRc) for intermittent exotropia in the setting of inferior oblique overaction. METHODS: A retrospective chart review was conducted of patients with intermittent exotropia who underwent LRc using adjustable sutures alone versus LRc combined with IOM between January 2010 and July 2018 at our institution. Binocular alignment was recorded before and within one week of surgery. Evaluation measures noted were surgical success (defined as distance alignment of ⩽10 prism diopters) and need for postoperative adjustment due to overcorrection. RESULTS: Of 48 patients, 24 underwent LRc alone and 24 underwent LRc combined with IOM; all 48 patients had adjustable sutures. Surgical success was significantly higher in the LRc alone group (91.6%) compared with the LRc with IOM group (62.5%) (p = 0.036). The need for postoperative adjustment due to overcorrection was also significantly higher in the LRc with IOM group (20.8%) compared with the LRc alone group (0%) (p = 0.049). CONCLUSIONS: In this study, more patients needed adjustment for overcorrection after undergoing LRc combined with IOM versus LRc alone. Since the tertiary action of the inferior oblique is abduction it is possible that, in patients with inferior oblique overaction, surgically weakening the inferior oblique causes more esodeviation and overcorrection. Thus, surgical correction of exotropia and inferior oblique overaction using LRc combined with IOM may lead to overcorrection and increased need for postoperative adjustment.

Diabetic retinopathy (DR) is a sight-threatening complication of diabetes mellitus (DM) and it contributes substantially to the burden of disease globally. During the last decades, the development of multiple imaging modalities to evaluate DR, combined with emerging treatment possibilities, has led to the implementation of large-scale screening programmes resulting in improved prevention of vision loss. However, not all patients are able to participate in such programmes and not all are at equal risk of DR development and progression. In this review, we discuss the relevance of the currently available imaging modalities for the evaluation of DR: colour fundus photography (CFP), ultrawide-field photography (UWFP), fundus fluorescein angiography (FFA), optical coherence tomography (OCT), OCT angiography (OCTA) and functional testing. Furthermore, we suggest where a particular imaging technique of DR may aid the evaluation of the disease in different clinical settings. Combining information from various imaging modalities may enable the design of more personalized care including the initiation of treatment and understanding the progression of disease more adequately.

Rod-cone dystrophy (RCD), also known as retinitis pigmentosa, is an inherited condition leading to vision loss, affecting 1 in 3500 people. More than 270 genes are known to be implicated in the inherited retinal degenerations (IRDs), yet genetic diagnosis for ∼30% of IRD of patients remains elusive despite advances in sequencing technologies. The goal of this study was to determine the genetic causality in a family with RCD. Family members were given a full ophthalmic exam at the Retinal Service at Massachusetts Eye and Ear and consented to genetic testing. Whole-exome sequencing (WES) was performed and variants of interest were Sanger-validated. Functional assays were conducted in zebrafish along with splicing assays in relevant cell lines to determine the impact on retinal function. WES identified variants in two potential candidate genes that segregated with disease: GNL3 (G Protein Nucleolar 3) c.1187 + 3A > C and c.1568-8C > A; and PDE4DIP (Phosphodiester 4D Interacting Protein) c.3868G > A (p.Glu1290Lys) and c.4603G > A (p.Ala1535Thr). Both genes were promising candidates based on their retinal involvement (development and interactions with IRD-associated proteins); however, the functional assays did not validate either gene. Subsequent WES reanalysis with an updated bioinformatics pipeline and widened search parameters led to the detection of a 94-bp duplication in PRPF31 (pre-mRNA Processing Factor 31) c.73_266dup (p.Asp56GlyfsTer33) as the causal variant. Our study demonstrates the importance of thorough functional characterization of new disease candidate genes and the value of reanalyzing next-generation sequencing sequence data, which in our case led to identification of a hidden pathogenic variant in a known IRD gene.

BACKGROUND/AIMS: Psychotropic medications have been reported as a risk factor for angle closure disease. However, the interaction between background genetic risk for primary angle closure glaucoma (PACG) and susceptibility to angle closure disease among psychotropic medication users has not been investigated. Here we demonstrate the utility of a genome-wide polygenic risk score (PRS) in identifying and risk-stratifying subjects with PACG and investigate the association between PACG genetic burden and exposure to psychotropic medications on prevalent angle closure. METHODS: This analysis used the UK Biobank dataset, a prospective cohort study of 502,506 UK residents. We constructed a PACG PRS for participants using genome-wide association study summary statistics from a multiethnic meta-analysis using the Lassosum method. RESULTS: Among the 441,054 participants, 959 (0.22%) were identified as PACG cases. Individuals with PACG had higher PRS compared to those without PACG (0.24±1.03 SD vs. 0.00±1.00 SD, p<0.001) and PACG prevalence increased with each decile of higher PRS. Among individuals using psychotropic medication, those with PACG had higher average PRS (0.31±1.00 SD vs. 0.00±1.00 SD, p<0.001) and were more likely to have a PRS in upper deciles of polygenic risk (p = 0.04). At each decile of PRS, psychotropic medication use was associated with increased risk of PACG. These effects were more pronounced and significant in higher deciles. CONCLUSION: We demonstrate the utility of a PRS for identifying individuals at higher risk of PACG. Additionally, we demonstrate an important relationship where the association between psychotropic medications use and PACG diagnosis varies across the polygenic risk spectrum.

Juvenile-onset open-angle glaucoma (JOAG) is a subset of primary open-angle glaucoma that is diagnosed before 40 years of age. The disease may be familial or non-familial, with proportions varying among different populations. Myocilin mutations are the most commonly associated. JOAG is characterized by high intraocular pressures (IOP), with many patients needing surgery. The mean age at diagnosis is in the 3rd decade, with a male preponderance. Myopia is a common association. The pathophysiology underlying the disease is immaturity of the conventional outflow pathways, which may or may not be observed on gonioscopy and anterior segment optical coherence tomography. The unique optic nerve head features include large discs with deep, steep cupping associated with high IOP-induced damage. Progression rates among JOAG patients are comparable to adult primary glaucomas, but as the disease affects younger patients, the projected disability from this disease is higher. Early diagnosis, prompt management, and life-long monitoring play an important role in preventing disease progression. Gene-based therapies currently under investigation offer future hope.

We describe in vivo follow-up PET imaging and postmortem findings from an autosomal dominant Alzheimer's disease (ADAD) PSEN1 E280A carrier who was also homozygous for the APOE3 Christchurch (APOE3ch) variant and was protected against Alzheimer's symptoms for almost three decades beyond the expected age of onset. We identified a distinct anatomical pattern of tau pathology with atypical accumulation in vivo and unusual postmortem regional distribution characterized by sparing in the frontal cortex and severe pathology in the occipital cortex. The frontal cortex and the hippocampus, less affected than the occipital cortex by tau pathology, contained Related Orphan Receptor B (RORB) positive neurons, homeostatic astrocytes and higher APOE expression. The occipital cortex, the only cortical region showing cerebral amyloid angiopathy (CAA), exhibited a distinctive chronic inflammatory microglial profile and lower APOE expression. Thus, the Christchurch variant may impact the distribution of tau pathology, modulate age at onset, severity, progression, and clinical presentation of ADAD, suggesting possible therapeutic strategies.

Background: Utilizing telemedicine is one approach to reduce the ever-increasing burden of patients on emergency departments (EDs) and consulting physicians. Utilization of telemedicine services in the ED may also benefit resident education. Materials and Methods: Ten first-year ophthalmology residents were trained to use a Topcon 3D Optical Coherence Tomography (OCT)-1 Maestro to capture OCT images and fundus photos in patients presenting to the ED with urgent ophthalmic concerns. Findings were communicated to the supervising ophthalmologist. Retrospective chart review was conducted to obtain patient characteristics and final ophthalmologist diagnosis. Residents rated ease of use, technical reliability, and educational value through a survey. Results: From December 1, 2019, to December 1, 2020, the device was used in 109 patient encounters, capturing 887 images (average 8.1 images per encounter). Patients on whom the device was used were on average 48.5 years old (±17.2, range 17-90) and 59.6% were female. The imaging device was utilized most commonly for evaluating papilledema (n = 21, 18.6%), new-onset visual acuity/visual field defects (n = 12, 10.6%), retinal detachment/tear (n = 8, 7.1%), and ophthalmic trauma workup (n = 8, 7.1%). Eight residents completed the survey and most (n = 7) agreed or strongly agreed that the device helped them diagnose patients more accurately. Technical issues such as machine malfunction, image artifacts, and problems syncing with the electronic health record and computer were noted by survey respondents. Conclusions: The most common use of teleophthalmology in the ED setting was evaluation of papilledema; the majority of residents perceived an educational benefit from this tool. Efforts should be made to address the technical challenges to increase the utility of this device.

Purpose: To report visual function and quality of life (VF/QOL) using the National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) and the ocular surface disease index (OSDI) in patients in the chronic phase of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Methods: The NEI-VFQ-25 questionnaire was administered to 15 patients who received protocol-based care in the form of topical medications with or without amniotic membrane transplantation (AMT) for acute SJS/TEN. The scores obtained were compared with scores from a healthy population. The associations between the NEI-VFQ-25 and dry eye symptoms as measured by OSDI questionnaire were also studied. Results: Patients were surveyed at a mean of 4.47 ± 2.22 years after acute SJS/TEN. Eleven patients received AMT in the acute phase. The median best corrected visual acuity at the time of administration of the questionnaire was 20/20. The mean composite NEI-VFQ-25 score was 86.48 ± 12. Patients who received protocol-based treatment in the acute phase of SJS/TEN had comparable NEI-VFQ-25 scores with healthy subjects on all subscales except ocular pain (p = 0.027) and mental health (p = 0.014), which were significantly reduced. The NEI-VFQ-25 composite scores significantly correlated with OSDI (R = -0.75, p = 0.001). Conclusion: A protocol-based management strategy composed of early ophthalmic evaluation, grading based on severity, the use of topical corticosteroids and AMT in the acute phase of SJS/TEN in patients with ocular complications helped preserve the VF/QOL. This study highlights the impact of appropriate management of the ocular complications in the acute phase of SJS/TEN.

INTRODUCTION: Mortality risk prediction is an important part of the clinical assessment in the Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) patient. The SCORTEN and ABCD-10 scoring systems have been used as predictive clinical tools for assessing this risk. However, some of the metrics required in calculating these scores, such as the total body surface area (TBSA) involvement, are difficult to calculate. In addition, TBSA involvement is calculated in a variety of ways and is observer dependent and subjective. The goal of this study was to develop an alternative method to predict mortality in patients with SJS/TEN. METHODS: Data was split into training and test datasets and preprocessed. Models were trained using five-fold cross validation. Out of several possible candidates, a random forests model was evaluated as being the most robust in predictive power for this dataset. Upon feature selection, a final random forests model was developed which was used for comparison against SCORTEN. RESULTS: The differences in both accuracy (p = 0.324) and area under the receiver operating characteristic curve (AUROC) (p = 0.318) between the final random forests model and the SCORTEN and ABCD-10 models were not statistically significant. As such, this alternative method performs similarly to SCORTEN while only requiring simple laboratory tests from the day of admission. DISCUSSION: This new alternative can make the mortality prediction process more efficient, along with providing a seamless implementation of the patient laboratory tests directly into the model from existing electronic health record (EHR) systems. Once the model was developed, a web application was built to deploy the model which integrates with the Epic EHR system on the Fast Healthcare Interoperability Resources (FHIR) Application Programming Interface (API); this only requires the patient medical record number and a date of the lab tests as parameters. This model ultimately allows clinicians to calculate patient mortality risk with only a few clicks. Further studies are needed for validation of this tool.

When ionizing irradiation interacts with a media, it can form reactive species that can react with the constituents of the system, leading to eradication of bioburden and sterilization of the tissue. Understanding the media's properties such as polarity is important to control and direct those reactive species to perform desired reactions. Using ethanol as a polarity modifier of water, we herein generated a series of media with varying relative polarities for electron beam (E-beam) irradiation of cornea at 25 kGy and studied how the irradiation media's polarity impacts properties of the cornea. After irradiation of corneal tissues, mechanical (tensile strength and modulus, elongation at break, and compression modulus), chemical, optical, structural, degradation, and biological properties of the corneal tissues were evaluated. Our study showed that irradiation in lower relative polarity media improved structural properties of the tissues yet reduced optical transmission; higher relative polarity reduced structural and optical properties of the cornea; and intermediate relative polarity (ethanol concentrations = 20-30% (v/v)) improved the structural properties, without compromising optical characteristics. Regardless of media polarity, irradiation did not negatively impact the biocompatibility of the corneal tissue. Our data shows that the absorbed ethanol can be flushed from the irradiated cornea to levels that are nontoxic to corneal and retinal cells. These findings suggest that the relative polarity of the irradiation media can be tuned to generate sterilized tissues, including corneal grafts, with engineered properties that are required for specific biomedical applications. STATEMENT OF SIGNIFICANCE: Extending the shelf-life of corneal tissue can improve general accessibility of cornea grafts for transplantation. Irradiation of donor corneas with E-beam is an emerging technology to sterilize the corneal tissues and enable their long-term storage at room temperature. Despite recent applications in clinical medicine, little is known about the effect of irradiation and preservation media's characteristics, such as polarity on the properties of irradiated corneas. Here, we have showed that the polarity of the media can be a valuable tool to change and control the properties of the irradiated tissue for transplantation.

Despite rigorous investigations, the hydrogels currently available to replace damaged tissues, such as the cornea, cannot fulfill mechanical and structural requirements and, more importantly, cannot be sutured into host tissues due to the lack of hierarchical structures to dissipate exerted stress. In this report, solution electrospinning of polycaprolactone (PCL), protein-based hydrogel perfusion, and layer-by-layer stacking are used to generate a hydrogel-microfiber composite with varying PCL fiber diameters and hydrogel concentrations. Integrating PCL microfibers into the hydrogel synergistically improves the mechanical properties and suturability of the construct up to 10-fold and 50-fold, respectively, compared to the hydrogel and microfiber scaffolds alone, approaching those of the corneal tissue. Human corneal cells cultured on composites are viable and can spread, proliferate, and retain phenotypic characteristics. Moreover, corneal stromal cells migrate into the scaffold, degrade it, and regenerate the extracellular matrix. The current hydrogel reinforcing system paves the way for producing suturable and, therefore, transplantable tissue constructs with desired mechanical properties.