From waste to wealth: Repurposing slaughterhouse waste for xenotransplantation

Integrated environmental and health economic assessments of novel xeno-keratografts addressing a growing public health crisis

Tissue scarcity poses global challenges for corneal transplantation and public health. Xeno-keratoplasty using animal-derived tissues offers a potential solution, but its environmental and economic implications remain unclear. This study evaluated two xeno-keratoplasty procedures at a single institution: (1) native corneas (Option 1) and (2) tissue-engineered corneal scaffolds derived from slaughterhouse waste (Option 2). Life cycle assessment (LCA) quantified environmental impacts across 18 midpoint indicators, while cost-effectiveness analysis (CEA) incorporated cost and environmental impact using two approaches. Option 1 exhibited significantly lower environmental impact than Option 2 across most indicators, primarily due to the energy and equipment demands of cell culture in Option 2. Both CEA approaches (carbon offset pricing and utility decrement) demonstrated cost-effectiveness dominance for Option 1. Xeno-keratoplasty using native corneas (Option 1) appears more environmentally and economically favorable than tissue-engineered scaffolds (Option 2) in the current analysis. Future studies could explore diverse xeno-keratoplasty techniques for optimizing sustainability.

Investigation of fatty acid profile of eyes recovered from slaughterhouse waste

Polyunsaturated fatty acids (PUFAs), principally Docosahexaenoic acid (DHA, 22:6n-3), the foremost omega-3 PUFAs in the brain and eyes, have been implicated in maintaining the structural and functional properties of the retina and cornea. Another PUFA, Arachidonic Acid (AA, 20:4n-6), primary omega-6 PUFA in the cell membrane of phospholipids, is a central inflammatory mediator involved in many molecular and cellular functions under physiological and pathological conditions, including dry eye disease (DED) and age-related macular degeneration (AMD). This study investigated the fatty acids (FA) composition of the vitreous humor, retina, cornea, and whole eye in two mammals, the Arabian sheep (Ovis aries) and Arabian camel (Camelus dromedarius), with the aim of exploring new paths for beneficial PUFA production. In Ovis aries, the retina exhibited the highest content in DHA and AA with 4.30 ± 0.63 % and 13.48 ± 1.33 % of the total fatty acid content, respectively. In Camelus dromedarius, the DHA content was greater in the retina compared to all samples, and AA was detected in the vitreous humor, cornea, retina, and whole eye, with the highest content in the retina (15.38 ± 0.71 %). Comparing both mammals, the DHA fraction was higher in camel's retina than in sheep's retina, whereas no differences were noticed for AA accumulation. In conclusion, ocular tissues collected from agri-food waste in slaughterhouses could serve as a sustainable source for FA production and provide an innovative and emerging prospect in the nutrition, pharmaceutical, and healthcare sectors.

Region-Specific Decellularization of Porcine Uterine Tube Extracellular Matrix: A New Approach for Reproductive Tissue-Engineering Applications

The uterine tube extracellular matrix is a key component that regulates tubal tissue physiology, and it has a region-specific structural distribution, which is directly associated to its functions. Considering this, the application of biological matrices in culture systems is an interesting strategy to develop biomimetic tubal microenvironments and enhance their complexity. However, there are no established protocols to produce tubal biological matrices that consider the organ morphophysiology for such applications. Therefore, this study aimed to establish region-specific protocols to obtain decellularized scaffolds derived from porcine infundibulum, ampulla, and isthmus to provide suitable sources of biomaterials for tissue-engineering approaches. Porcine uterine tubes were decellularized in solutions of 0.1% SDS and 0.5% Triton X-100. The decellularization efficiency was evaluated by DAPI staining and DNA quantification. We analyzed the ECM composition and structure by optical and scanning electronic microscopy, FTIR, and Raman spectroscopy. DNA and DAPI assays validated the decellularization, presenting a significative reduction in cellular content. Structural and spectroscopy analyses revealed that the produced scaffolds remained well structured and with the ECM composition preserved. YS and HEK293 cells were used to attest cytocompatibility, allowing high cell viability rates and successful interaction with the scaffolds. These results suggest that such matrices are applicable for future biotechnological approaches in the reproductive field.

A sustainable approach to derive sheep corneal scaffolds from stored slaughterhouse waste

Aim: The escalating demand for corneal transplants significantly surpasses the available supply. To bridge this gap, we concentrated on ethical and sustainable corneal grafting sources. Our objective was to create viable corneal scaffolds from preserved slaughterhouse waste.Materials & methods: Corneas were extracted and decellularized from eyeballs that had been refrigerated for several days. These scaffolds underwent evaluation through DNA quantification, histological analysis, surface tension measurement, light propagation testing, and tensile strength assessment.Results: Both the native and acellular corneas (with ~90% DNA removed using a cost-effective and environmentally friendly surfactant) maintained essential optical and biomechanical properties for potential clinical use.Conclusion: Our method of repurposing slaughterhouse waste, stored at 4°C for several days, to develop corneal scaffolds offers a sustainable and economical alternative xenograft model.

Decellularized Bovine Skeletal Muscle Scaffolds: Structural Characterization and Preliminary Cytocompatibility Evaluation

Skeletal muscle degeneration is responsible for major mobility complications, and this muscle type has little regenerative capacity. Several biomaterials have been proposed to induce muscle regeneration and function restoration. Decellularized scaffolds present biological properties that allow efficient cell culture, providing a suitable microenvironment for artificial construct development and being an alternative for in vitro muscle culture. For translational purposes, biomaterials derived from large animals are an interesting and unexplored source for muscle scaffold production. Therefore, this study aimed to produce and characterize bovine muscle scaffolds to be applied to muscle cell 3D cultures. Bovine muscle fragments were immersed in decellularizing solutions for 7 days. Decellularization efficiency, structure, composition, and three-dimensionality were evaluated. Bovine fetal myoblasts were cultured on the scaffolds for 10 days to attest cytocompatibility. Decellularization was confirmed by DAPI staining and DNA quantification. Histological and immunohistochemical analysis attested to the preservation of main ECM components. SEM analysis demonstrated that the 3D structure was maintained. In addition, after 10 days, fetal myoblasts were able to adhere and proliferate on the scaffolds, attesting to their cytocompatibility. These data, even preliminary, infer that generated bovine muscular scaffolds were well structured, with preserved composition and allowed cell culture. This study demonstrated that biomaterials derived from bovine muscle could be used in tissue engineering.

Barriers toward xenotransplantation in Arab World

Organ transplant is a crucial therapeutic strategy offering a life-saving and transformative medical intervention. It provides an opportunity to improve their quality of life and increase their lifespan. The shortage of organs remains a critical global challenge, leading to a prolonged waiting times for organ receivers, which contributes to an increase in morbidity and mortality rates. Hence, xenotransplantation offered a promising solution to the global shortage of organs through the use of animal organs, leading to an increase in donor availability, reducing waiting times, minimizing organ trafficking, improving genetic engineering advancements, and driving scientific innovation. Even though xenotransplantation has many benefits in the clinical setting, it has many barriers that are hindering its achievements and constraining its occurrence. Some barriers to xenotransplant are general, such as the immunological barrier, while others are specific to certain regions due to local causes. The Arab region exhibits disparities in clinical settings compared to the global context, marked by the huge economic crisis and a shortage of trained healthcare professionals. Considering the huge resources and advancements needed in the field of xenotransplantation, this review aims to explore the specific barriers toward xenotransplantation in the Arab countries, highlighting the challenges to overcome these barriers.

Recellularization of Acellular Xeno Kidney Scaffold: An In Vivo Method to Generate Bioartificial Kidney

A significant hurdle for kidney tissue engineering is reproducing the complex three-dimensional structure of the kidney. In our study, a stepwise approach of generating a reproducible Xeno kidney scaffold from a goat kidney is described, which can be implanted and recellularized by host cells. We have proposed a combination of sodium dodecyl sulfate and Triton-X-100-based protocol to generate a reproducible Xeno kidney scaffold, which was then analyzed by histology, DNA quantification, SEM, and renal angiography. Further, a small portion from the cortico-medullar region of the acellular scaffold was implanted in the rat's kidney subcapsular pocket for a period of 1 month, to check the recruitment of host cells into the scaffold. Post implantation, the extracellular matrix of the scaffold was well preserved and it did not induce any damage or inflammation in the native kidney. Implantation of the Xeno scaffold resulted in apparent early vascularization which helped in the recruitment of the host cells, which was characterized by histology, immunohistochemistry, and scanning electron microscopy. Implanted Xeno scaffold showed AQP-1, Nephrin, α-SMA, and VEGF expression in proximal tubules and renal glomerulus. Importantly, Ki-67 and WTAP-expressing cells were also observed near proximal tubules suggesting a high level of proliferation in the scaffold. Thus, showing the potential of Xeno kidney development that can be recellularized by the host cell to engineer into a functional kidney.

A proposed model of xeno-keratoplasty using 3D printing and decellularization

Corneal opacity is a leading cause of vision impairment and suffering worldwide. Transplantation can effectively restore vision and reduce chronic discomfort. However, there is a considerable shortage of viable corneal graft tissues. Tissue engineering may address this issue by advancing xeno-keratoplasty as a viable alternative to conventional keratoplasty. In particular, livestock decellularization strategies offer the potential to generate bioartificial ocular prosthetics in sufficient supply to match existing and projected needs. To this end, we have examined the best practices and characterizations that have supported the current state-of-the-art driving preclinical and clinical applications. Identifying the challenges that delimit activities to supplement the donor corneal pool derived from acellular scaffolds allowed us to hypothesize a model for keratoprosthesis applications derived from livestock combining 3D printing and decellularization.

Computational approaches for evaluating morphological changes in the corneal stroma associated with decellularization

Decellularized corneas offer a promising and sustainable source of replacement grafts, mimicking native tissue and reducing the risk of immune rejection post-transplantation. Despite great success in achieving acellular scaffolds, little consensus exists regarding the quality of the decellularized extracellular matrix. Metrics used to evaluate extracellular matrix performance are study-specific, subjective, and semi-quantitative. Thus, this work focused on developing a computational method to examine the effectiveness of corneal decellularization. We combined conventional semi-quantitative histological assessments and automated scaffold evaluations based on textual image analyses to assess decellularization efficiency. Our study highlights that it is possible to develop contemporary machine learning (ML) models based on random forests and support vector machine algorithms, which can identify regions of interest in acellularized corneal stromal tissue with relatively high accuracy. These results provide a platform for developing machine learning biosensing systems for evaluating subtle morphological changes in decellularized scaffolds, which are crucial for assessing their functionality.

A scalable corneal xenograft platform: simultaneous opportunities for tissue engineering and circular economic sustainability by repurposing slaughterhouse waste

Introduction: Corneal disease is a leading cause of blindness globally that stems from various etiologies. High-throughput platforms that can generate substantial quantities of corneal grafts will be invaluable in addressing the existing global demand for keratoplasty. Slaughterhouses generate substantial quantities of underutilized biological waste that can be repurposed to reduce current environmentally unfriendly practices. Such efforts to support sustainability can simultaneously drive the development of bioartificial keratoprostheses. Methods: Scores of discarded eyes from the prominent Arabian sheep breeds in our surrounding region of the United Arab Emirates (UAE) were repurposed to generate native and acellular corneal keratoprostheses. Acellular corneal scaffolds were created using a whole-eye immersion/agitation-based decellularization technique with a widely available, eco-friendly, and inexpensive 4% zwitterionic biosurfactant solution (Ecover, Malle, Belgium). Conventional approaches like DNA quantification, ECM fibril organization, scaffold dimensions, ocular transparency and transmittance, surface tension measurements, and Fourier-transform infrared (FTIR) spectroscopy were used to examine corneal scaffold composition. Results: Using this high-throughput system, we effectively removed over 95% of the native DNA from native corneas while retaining the innate microarchitecture that supported substantial light transmission (over 70%) after reversing opacity, a well-established hallmark of decellularization and long-term native corneal storage, with glycerol. FTIR data revealed the absence of spectral peaks in the frequency range 2849 cm-1 to 3075 cm-1, indicating the effective removal of the residual biosurfactant post-decellularization. Surface tension studies confirmed the FTIR data by capturing the surfactant's progressive and effectual removal through tension measurements ranging from approximately 35 mN/m for the 4% decellularizing agent to 70 mN/m for elutes highlighting the effective removal of the detergent. Discussion: To our knowledge, this is the first dataset to be generated outlining a platform that can produce dozens of ovine acellular corneal scaffolds that effectively preserve ocular transparency, transmittance, and ECM components using an eco-friendly surfactant. Analogously, decellularization technologies can support corneal regeneration with attributes comparable to native xenografts. Thus, this study presents a simplified, inexpensive, and scalable high-throughput corneal xenograft platform to support tissue engineering, regenerative medicine, and circular economic sustainability.

Capturing effects of blood flow on the transplanted decellularized nephron with intravital microscopy

Organ decellularization creates cell-free, collagen-based extracellular matrices that can be used as scaffolds for tissue engineering applications. This technique has recently gained much attention, yet adequate scaffold repopulation and implantation remain a challenge. Specifically, there still needs to be a greater understanding of scaffold responses post-transplantation and ways we can improve scaffold durability to withstand the in vivo environment. Recent studies have outlined vascular events that limit organ decellularization/recellularization scaffold viability for long-term transplantation. However, these insights have relied on in vitro/in vivo approaches that need enhanced spatial and temporal resolutions to investigate such issues at the microvascular level. This study uses intravital microscopy to gain instant feedback on their structure, function, and deformation dynamics. Thus, the objective of this study was to capture the effects of in vivo blood flow on the decellularized glomerulus, peritubular capillaries, and tubules after autologous and allogeneic orthotopic transplantation into rats. Large molecular weight dextran molecules labeled the vasculature. They revealed substantial degrees of translocation from glomerular and peritubular capillary tracks to the decellularized tubular epithelium and lumen as early as 12 h after transplantation, providing real-time evidence of the increases in microvascular permeability. Macromolecular extravasation persisted for a week, during which the decellularized microarchitecture was significantly and comparably compromised and thrombosed in both autologous and allogeneic approaches. These results indicate that in vivo multiphoton microscopy is a powerful approach for studying scaffold viability and identifying ways to promote scaffold longevity and vasculogenesis in bioartificial organs.

Gray level co-occurrence matrix and wavelet analyses reveal discrete changes in proximal tubule cell nuclei after mild acute kidney injury

Acute kidney injury (AKI) relates to an abrupt reduction in renal function resulting from numerous conditions. Morbidity, mortality, and treatment costs related to AKI are relatively high. This condition is strongly associated with damage to proximal tubule cells (PTCs), generating distinct patterns of transcriptional and epigenetic alterations that result in structural changes in the nuclei of this epithelium. To this date, AKI-related nuclear chromatin redistribution in PTCs is poorly understood, and it is unclear whether changes in PTC chromatin patterns can be detected using conventional microscopy during mild AKI, which can progress to more debilitating forms of injury. In recent years, gray level co-occurrence matrix (GLCM) analysis and discrete wavelet transform (DWT) have emerged as potentially valuable methods for identifying discrete structural changes in nuclear chromatin architecture that are not visible during the conventional histopathological exam. Here we present findings indicating that GLCM and DWT methods can be successfully used in nephrology to detect subtle nuclear morphological alterations associated with mild tissue injury demonstrated in rodents by inducing a mild form of AKI through ischemia-reperfusion injury. Our results show that mild ischemic AKI is associated with the reduction of local textural homogeneity of PTC nuclei quantified by GLCM and the increase of nuclear structural heterogeneity indirectly assessed with DWT energy coefficients. This rodent model allowed us to show that mild ischemic AKI is associated with the significant reduction of textural homogeneity of PTC nuclei, indirectly assessed by GLCM indicators and DWT energy coefficients.

Enhancing the expression of a key mitochondrial enzyme at the inception of ischemia-reperfusion injury can boost recovery and halt the progression of acute kidney injury

Hydrodynamic fluid delivery has shown promise in influencing renal function in disease models. This technique provided pre-conditioned protection in acute injury models by upregulating the mitochondrial adaptation, while hydrodynamic injections of saline alone have improved microvascular perfusion. Accordingly, hydrodynamic mitochondrial gene delivery was applied to investigate the ability to halt progressive or persistent renal function impairment following episodes of ischemia-reperfusion injuries known to induce acute kidney injury (AKI). The rate of transgene expression was approximately 33% and 30% in rats with prerenal AKI that received treatments 1 (T1hr) and 24 (T24hr) hours after the injury was established, respectively. The resulting mitochondrial adaptation via exogenous IDH2 (isocitrate dehydrogenase 2 (NADP+) and mitochondrial) significantly blunted the effects of injury within 24 h of administration: decreased serum creatinine (≈60%, p < 0.05 at T1hr; ≈50%, p < 0.05 at T24hr) and blood urea nitrogen (≈50%, p < 0.05 at T1hr; ≈35%, p < 0.05 at T24hr) levels, and increased urine output (≈40%, p < 0.05 at T1hr; ≈26%, p < 0.05 at T24hr) and mitochondrial membrane potential, Δψm, (≈ by a factor of 13, p < 0.001 at T1hr; ≈ by a factor of 11, p < 0.001 at T24hr), despite elevated histology injury score (26%, p < 0.05 at T1hr; 47%, p < 0.05 at T24hr). Therefore, this study identifies an approach that can boost recovery and halt the progression of AKI at its inception.

Still finding ways to augment the existing management of acute and chronic kidney diseases with targeted gene and cell therapies: Opportunities and hurdles

The rising global incidence of acute and chronic kidney diseases has increased the demand for renal replacement therapy. This issue, compounded with the limited availability of viable kidneys for transplantation, has propelled the search for alternative strategies to address the growing health and economic burdens associated with these conditions. In the search for such alternatives, significant efforts have been devised to augment the current and primarily supportive management of renal injury with novel regenerative strategies. For example, gene- and cell-based approaches that utilize recombinant peptides/proteins, gene, cell, organoid, and RNAi technologies have shown promising outcomes primarily in experimental models. Supporting research has also been conducted to improve our understanding of the critical aspects that facilitate the development of efficient gene- and cell-based techniques that the complex structure of the kidney has traditionally limited. This manuscript is intended to communicate efforts that have driven the development of such therapies by identifying the vectors and delivery routes needed to drive exogenous transgene incorporation that may support the treatment of acute and chronic kidney diseases.