Biomechanical and morphological stability of acellular scaffolds for tissue-engineered heart valves depends on different storage conditions

Mechanical and Structural Adaptation of the Pulmonary Root after Ross Operation in a Murine Model

Background: The major limitation to the Ross operation is a progressive autograft dilation, possibly leading to reoperations. A murine model was created to evaluate pulmonary artery graft (PAG) adaptation to pressure overload. Methods: Lewis rats (n = 17) underwent heterotopic surgical implantation of a PAG, harvested from syngeneic animals (n = 17). A group of sham animals (n = 7) was used as a control. Seriated ultrasound studies of the PAG were performed. Animals were sacrificed at 1 week (n = 5) or 2 months (n = 15) and the PAG underwent mechanical and histopathological analyses. Results: Echography showed an initial increase in diameter (p < 0.001) and a decrease in peak systolic velocity (PSV). Subsequently, despite no change in diameter, an increase in PSV was observed (p < 0.01). After 1 week, the stiffness of the PAG and the aorta were similar, while at 2 months, the PAG appeared more rigid (p < 0.05). PAG’s histological analysis at 2 months revealed intimal hyperplasia development. The tunica media showed focal thinning of the elastic lamellae and normally distributed smooth muscle cells. Conclusions: We demonstrated a stiffening of the PAG wall after its implantation in systemic position; the development of intimal hyperplasia and the thinning of the elastic lamellae could be the possible underlying mechanism.

Recent Advances in Scaffolding from Natural-Based Polymers for Volumetric Muscle Injury

Volumetric Muscle Loss (VML) is associated with muscle loss function and often untreated and considered part of the natural sequelae of trauma. Various types of biomaterials with different physical and properties have been developed to treat VML. However, much work remains yet to be done before the scaffolds can pass from the bench to the bedside. The present review aims to provide a comprehensive summary of the latest developments in the construction and application of natural polymers-based tissue scaffolding for volumetric muscle injury. Here, the tissue engineering approaches for treating volumetric muscle loss injury are highlighted and recent advances in cell-based therapies using various sources of stem cells are elaborated in detail. An overview of different strategies of tissue scaffolding and their efficacy on skeletal muscle cells regeneration and migration are presented. Furthermore, the present paper discusses a wide range of natural polymers with a special focus on proteins and polysaccharides that are major components of the extracellular matrices. The natural polymers are biologically active and excellently promote cell adhesion and growth. These bio-characteristics justify natural polymers as one of the most attractive options for developing scaffolds for muscle cell regeneration.

The useful agent to have an ideal biological scaffold

Tissue engineering which is applied in regenerative medicine has three basic components: cells, scaffolds and growth factors. This multidisciplinary field can regulate cell behaviors in different conditions using scaffolds and growth factors. Scaffolds perform this regulation with their structural, mechanical, functional and bioinductive properties and growth factors by attaching to and activating their receptors in cells. There are various types of biological extracellular matrix (ECM) and polymeric scaffolds in tissue engineering. Recently, many researchers have turned to using biological ECM rather than polymeric scaffolds because of its safety and growth factors. Therefore, selection the right scaffold with the best properties tailored to clinical use is an ideal way to regulate cell behaviors in order to repair or improve damaged tissue functions in regenerative medicine. In this review we first divided properties of biological scaffold into intrinsic and extrinsic elements and then explain the components of each element. Finally, the types of scaffold storage methods and their advantages and disadvantages are examined.

Development and Characterization of a Benchtop Corneal Puncture Injury Model

During recent military operations, eye-related injuries have risen in frequency due to increased use of explosive weaponry which often result in corneal puncture injuries. These have one of the poorest visual outcomes for wounded soldiers, often resulting in blindness due to the large variations in injury shape, size, and severity. As a result, improved therapeutics are needed which can stabilize the injury site and promote wound healing. Unfortunately, current corneal puncture injury models are not capable of producing irregularly shaped, large, high-speed injuries as seen on the battlefield, making relevant therapeutic development challenging. Here, we present a benchtop corneal puncture injury model for use with enucleated eyes that utilizes a high-speed solenoid device suitable for creating military-relevant injuries. We first established system baselines and ocular performance metrics, standardizing the different aspects of the benchtop model to ensure consistent results and properly account for tissue variability. The benchtop model was evaluated with corneal puncture injury objects up to 4.2 mm in diameter which generated intraocular pressure levels exceeding 1500 mmHg. Overall, the created benchtop model provides an initial platform for better characterizing corneal puncture injuries as seen in a military relevant clinical setting and a realistic approach for assessing potential therapeutics.

Status of Plant Protein-Based Green Scaffolds for Regenerative Medicine Applications

In recent decades, regenerative medicine has merited substantial attention from scientific and research communities. One of the essential requirements for this new strategy in medicine is the production of biocompatible and biodegradable scaffolds with desirable geometric structures and mechanical properties. Despite such promise, it appears that regenerative medicine is the last field to embrace green, or environmentally-friendly, processes, as many traditional tissue engineering materials employ toxic solvents and polymers that are clearly not environmentally friendly. Scaffolds fabricated from plant proteins (for example, zein, soy protein, and wheat gluten), possess proper mechanical properties, remarkable biocompatibility and aqueous stability which make them appropriate green biomaterials for regenerative medicine applications. The use of plant-derived proteins in regenerative medicine has been especially inspired by green medicine, which is the use of environmentally friendly materials in medicine. In the current review paper, the literature is reviewed and summarized for the applicability of plant proteins as biopolymer materials for several green regenerative medicine and tissue engineering applications.