Human Endothelial Cell Seeding in Partially Decellularized Kidneys

Current strategies on kidney regeneration using tissue engineering approaches: a systematic review

INTRODUCTION

Over the past two decades, there has been a notable rise in the number of individuals afflicted with End-Stage Renal Disease, resulting in an increased demand for renal replacement therapies. While periodic dialysis is beneficial, it can negatively impact a patient's quality of life and does not fully replicate the secretory functions of the kidneys. Additionally, the scarcity of organ donors and complications associated with organ transplants have underscored the importance of tissue engineering. Regenerative medicine is revolutionized by developing decellularized organs and tissue engineering, which is considered a cutting-edge area of study with enormous potential. Developing bioengineered kidneys using tissue engineering approaches for renal replacement therapy is promising.

METHOD AND MATERIALS

We aimed to systematically review the essential preclinical data to promote the translation of tissue engineering research for kidney repair from the laboratory to clinical practice. A PubMed search strategy was systematically implemented without any linguistic restrictions. The assessment focused on complete circumferential and inlay procedures, thoroughly evaluating parameters such as cell seeding, decellularization techniques, recellularization protocols, and biomaterial types.

RESULTS

Of the 1,484 studies retrieved from the following primary searches, 105 were included. Kidneys were harvested from eight different species. Nine studies performed kidney decellularization from discarded human kidneys. Sixty-four studies performed whole organ decellularization. Some studies used acellular scaffolds to produce hydrogels, sheets, and solutions. Decellularization is achieved through physical, chemical, or enzymatic treatment or a combination of them. Sterilization of acellular scaffolds was also thoroughly and comparatively evaluated. Lastly, different recellularization protocols and types of cells used for further cell seeding were demonstrated.

CONCLUSION

A comprehensive review of the existing literature about kidney tissue engineering was conducted to evaluate its effectiveness in preclinical investigations. Our findings indicate that enhancements in the design of preclinical studies are necessary to facilitate the successful translation of tissue engineering technologies into clinical applications.

Efficient decellularization of human fetal kidneys through optimized SDS exposure

Chronic kidney disease poses a significant threat to public health. Renal replacement therapy is the primary treatment option for end-stage kidney disease. However, there is a promising and relatively new method in regenerative medicine for creating a functional organ known as whole kidney decellularization. This method uses the intrinsic vasculature to perfuse the decellularizing agent into the tissue, effectively penetrating and removing cellular material. The regenerated bioscaffolds could serve as a source of organ donation. This study is focused on evaluating the effectiveness of various SDS exposures in decellularizing human fetal kidneys. The study included human fetal kidneys harvested from fetuses terminated before 14 weeks of gestational age. Kidneys were divided into six treatment groups based on SDS concentration and duration of perfusion. Decellularization, scanning electron microscopy, histopathological staining, immunofluorescent staining, and immunohistochemistry staining were performed to evaluate the adequacy of the process. The statistical analysis revealed that the SDS 0.1% treatment group had the highest collagen deposition after 24 h, significantly greater than the SDS 0.5% treatment group at 24 and 48 h. No significant differences were observed among the other treatment groups. The study concludes that the SDS 0.1% treatment group for 24 h was the most effective in terms of ECM content preservation and effective cell removal. This treatment showed better results than the other treatment groups and can be considered for future whole kidney decellularization studies.

Bioengineering of vascularized porcine flaps using perfusion-recellularization

Large volume soft tissue defects greatly impact patient quality of life and function while suitable repair options remain a challenge in reconstructive surgery. Engineered flaps could represent a clinically translatable option that may circumvent issues related to donor site morbidity and tissue availability. Herein, we describe the regeneration of vascularized porcine flaps, specifically of the omentum and tensor fascia lata (TFL) flaps, using a tissue engineering perfusion-decellularization and recellularization approach. Flaps were decellularized using a low concentration sodium dodecyl sulfate (SDS) detergent perfusion to generate an acellular scaffold with retained extracellular matrix (ECM) components while removing underlying cellular and nuclear contents. A perfusion-recellularization strategy allowed for seeding of acellular flaps with a co-culture of human umbilical vein endothelial cell (HUVEC) and mesenchymal stromal cells (MSC) onto the decellularized omentum and TFL flaps. Our recellularization technique demonstrated evidence of intravascular cell attachment, as well as markers of endothelial and mesenchymal phenotype. Altogether, our findings support the potential of using bioengineered porcine flaps as a novel, clinically-translatable strategy for future application in reconstructive surgery.

Research progress of biomaterials and innovative technologies in urinary tissue engineering

Substantial interests have been attracted to multiple bioactive and biomimetic biomaterials in recent decades because of their ability in presenting a structural and functional reconstruction of urinary tissues. Some innovative technologies have also been surging in urinary tissue engineering and urological regeneration by providing insights into the physiological behavior of the urinary system. As such, the hierarchical structure and tissue function of the bladder, urethra, and ureter can be reproduced similarly to the native urinary tissues. This review aims to summarize recent advances in functional biomaterials and biomimetic technologies toward urological reconstruction. Various nanofirous biomaterials derived from decellularized natural tissues, synthetic biopolymers, and hybrid scaffolds were developed with desired microstructure, surface chemistry, and mechanical properties. Some growth factors, drugs, as well as inorganic nanomaterials were also utilized to enhance the biological activity and functionality of scaffolds. Notably, it is emphasized that advanced approaches, such as 3D (bio) printing and organoids, have also been developed to facilitate structural and functional regeneration of the urological system. So in this review, we discussed the fabrication strategies, physiochemical properties, and biofunctional modification of regenerative biomaterials and their potential clinical application of fast-evolving technologies. In addition, future prospective and commercial products are further proposed and discussed.

Angiogenesis and Re-endothelialization in decellularized scaffolds: Recent advances and current challenges in tissue engineering

Decellularization of tissues and organs has recently become a promising approach in tissue engineering and regenerative medicine to circumvent the challenges of organ donation and complications of transplantations. However, one main obstacle to reaching this goal is acellular vasculature angiogenesis and endothelialization. Achieving an intact and functional vascular structure as a vital pathway for supplying oxygen and nutrients remains the decisive challenge in the decellularization/re-endothelialization procedure. In order to better understand and overcome this issue, complete and appropriate knowledge of endothelialization and its determining variables is required. Decellularization methods and their effectiveness, biological and mechanical characteristics of acellular scaffolds, artificial and biological bioreactors, and their possible applications, extracellular matrix surface modification, and different types of utilized cells are factors affecting endothelialization consequences. This review focuses on the characteristics of endothelialization and how to optimize them, as well as discussing recent developments in the process of re-endothelialization.