Decellularized scaffolds in regenerative medicine

Abstract

Allogeneic organ transplantation remains the ultimate solution for end-stage organ failure. Yet, the clinical application is limited by the shortage of donor organs and the need for lifelong immunosuppression, highlighting the importance of developing effective therapeutic strategies. In the field of regenerative medicine, various regenerative technologies have lately been developed using various biomaterials to address these limitations. Decellularized scaffolds, derived mainly from various non-autologous organs, have been proved a regenerative capability in vivo and in vitro and become an emerging treatment approach. However, this regenerative capability varies between scaffolds as a result of the diversity of anatomical structure and cellular composition of organs used for decellularization. Herein, recent advances in scaffolds based on organ regeneration in vivo and in vitro are highlighted along with aspects where further investigations and analyses are needed.

Keywords: decellularized scaffold; extracellular matrix; in vivo/in vitro; organ; regeneration.

Figure 1. Schematic diagram of liver regeneration hypothesis using decellularized scaffolds

A. Partial resection of one hepatic lobule is operated. B. The defected part is replaced with decellularized liver scaffold. C. Cells in the residential liver cross the suture border and regenerate on the liver scaffold.

Figure 2. Fabrication, vascular cast, light microstructure and implantation of decellularized liver scaffolds

A. Progressing decellularization of a single lobe of rat liver under continuous detergent perfusion. Scale bar 10mm. B. Decellularized whole liver scaffold with hepatic artery intact. Scale bar 20mm. C. Vessel corrosion casting of microstructure of the hepatic portal vein (blue), the hepatic artery (red) and the hepatic duct (transparent). Scale bar 2mm. H. & E. staining of liver matrix shows existence of blue-stained nuclei in intact liver D. but not in decellularized liver scaffold (E.). F., H. & E. staining results show the border between the liver parenchyma and implanted decellularized scaffold. Scale bar 100μm.

Figure 3. Proliferation of cells in the decellularized kidney scaffolds in vitro.

A. B. Double immunofluorescence shows the scaffold and the HUVEC with fibronectin (green) and CD31 (red), respectively. On the third day, adhered HUVECs are increased. On the seventh day, HUVECs adhere to the wall of median renal vessel-like structure in the scaffolds. C..D. The magnification pictures show the white squares in Figure. E. F. Fluorescence micrographs of a re-endothelialized kidney constructs. CD31 positive (red) and DAPI-positive HUVECs line the vascular tree across the entire graft cross section (image reconstruction, left) and form a monolayer to glomerular capillaries (right; white arrowheads indicate endothelial cells). G.-J. Fluorescence micrographs of re-endothelialized and re-epithelialized kidney constructs showing engraftment of podocin-expressing cells (green) and endothelial cells (CD31 positive; red) in a glomerulus (left; white arrowheads indicate Bowman's capsule and the asterisk indicates the vascular pole); engraftment of Na/K-ATPase-expressing cells (green) in a basolateral distribution in tubuli resembling proximal tubular structures with the appropriate nuclear polarity (left middle); engraftment of E-cadherin-expressing cells in tubuli resembling distal tubular structures (right middle); and a three-dimensional reconstruction of a re-endothelialized vessel leading into a glomerulus (white arrowheads indicate Bowman's capsule, and the asterisk indicates the vascular pole). T, tubule; Ptc, peritubular capillary. A.-D. Republished with permission of the Impact journals, from Jin et al. [33]; and E.-J. Reprinted from Song et al. [34] with permission from NPG, permission conveyed through Copyright Clearance Center, Inc. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.).

Figure 4. Fabrication and implantation of decellularized kidney scaffolds

A. With continuous detergent perfusion, the rat decellularzied kidney scaffold show different gross appearance. Scale bar 10mm. B. Casting model of decelluarized kidney scaffolds show intact microvessels. C. Decellularized scaffolds was sutured to a rat underwent partial nephrectomy. D. Macroscopic images show longitudinal cross-sections of whole experimental kidneys observation under stereoscopic microscope. Scale bar 20mm. E. Electron microscopy observation shows intact extracellular matrix in decellularized kidney scaffold. Scale bar 2μm. F. Radionuclide scanning analysis of experimental kidneys. G. H&E staining shows the border between the renal parenchyma and implanted decellularized scaffold. Scale bar 100μm.