Slaughterhouse waste: a unique and sustainable source for dECM-based bioinks

End-stage tissue and organ failure, stemming from an array of factors such as diseases, injuries, and developmental anomalies, has evolved into major economic and healthcare problems. Currently, standard clinical approaches to tackle these issues rely on organ donation. However, the shortage of donors and growing recipient pools limit the reliance on transplantation [1]. In fact, back in 2011, studies estimated that merely a third of patients in need of transplantation would receive one, and the overall likelihood of someone needing a transplant far outweighed their ability to become a donor [2]. Sadly, modern-day statistics fail to provide a better outlook. The rising incidences of debilitating conditions, along with substantial logistical constraints that affect successful transplantation, support trends pointing to a growing mismatch between tissue/organ supply and demand. These pervasive issues emphasize the need for alternative solutions to tackle the substantial global shortage.

To address this pressing medical necessity, tissue engineering approaches have emerged as viable solutions. These multidisciplinary fields combine knowledge and technologies from a diverse spectrum of areas, including biology, chemistry, engineering, medicine, pharmacology, materials science and, more recently, artificial intelligence [3]. Their primary goal is to develop treatments and innovations for repairing or replacing damaged tissues and organs [4]. Tissue engineering employs a wide range of techniques to design and create artificial/bio-artificial constructs. This process involves assembling biomimetic materials encompassing scaffolds, cells and signaling molecules to replicate natural tissue architectures and functions, thereby offering promising solutions to meet the growing demand for transplantation [5].

One of the most promising techniques within the field of tissue engineering is 3D bioprinting because of its versatility, ease of use, and precision of the fabrication process. 3D bioprinting, also known as additive manufacturing, is a process of joining materials layer-by-layer to build a framework that mimics native tissue architectures. This innovative approach has many applications, such as generating skin grafts for burn victims, cartilage and bone replacements for orthopedic procedures, nervous system repair, cornea replacement and vascularized tissues [6].

A key component of adaptive manufacturing is the bioink, which is a specialized natural or synthetic material infused with living cells, growth factors, and other bioactive compounds. A bioink should possess desired physicochemical properties, such as proper biomechanical, rheological, and biochemical characteristics of the target tissues. They are composed of a variety of materials, including natural polymers such as alginate and collagen, synthetic polymers like polyethylene glycol (PEG), and even the decellularized extracellular matrix (dECM) [7].

The dECM is typically derived from cadaveric sources, as well as laboratory bovine, ovine, murine, porcine, and simian tissues that share anatomical and physiological similarities with humans, including. In recent years, dECM components have been used in models for biomaterials-based biofabrication [8]. These dECM components can be homogenized into solutions containing bioactive cues that recapitulate a natural cellular environment. Such an environment will synergistically provide physical barriers, anchorage sites, and pathways for cellular growth, migration, and differentiation – essential for morphogenesis and a basic set of fundamental criteria for designing functional human tissues and organs.

We recognize the untapped potential of dECM derivatives found in animal tissues from livestock. Domestically raised animals, which are routinely slaughtered for food production, contribute to approximately 150 million tonnes of organic waste annually. This waste is notably rich in key bioink components like collagen, elastin, fibronectin, and hyaluronic acid [9]. As such, repurposing slaughterhouse waste offers a viable and sustainable method for producing hydrogels, tailored to specific tissue needs and cost-effective in nature. These hydrogels are adept at encapsulating desired cells and can be cross-linked or stabilized during or immediately after the bioprinting process, which is vital for achieving the precise shape, structure and architecture of the intended bioprinted construct [10].

This commentary underscores the significant aspects of developing bioinks from slaughterhouse waste. It highlights the abundance of available starter materials, outlines formulation and classification techniques, and discusses the derivation of these materials from discarded dECM sources. The repurposing of such waste not only presents a solution to an environmental problem but also unlocks new possibilities in the realm of tissue engineering and regenerative medicine.

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