Why Decellularized Tracheal Cartilage Tissue Post-Transplantation Does Not Show Bluish-Purple Color in H&E Staining

By Dr.Gitonga Muriithi

Introduction: Hematoxylin and Eosin (H&E) staining is a standard histological technique used to differentiate cellular and structural tissue components. In this staining method, hematoxylin stains basophilic structures (primarily nucleic acids in the nucleus) a blue to purple color, while eosin stains acidophilic structures (cytoplasmic proteins and extracellular matrix) in varying shades of pink.

Decellularization and Its Histological Consequences: Decellularization is the process of removing cellular components from tissues or organs to leave behind an extracellular matrix (ECM) scaffold, with the aim of reducing immunogenicity in grafts. When tracheal cartilage is decellularized:

• Nuclei and cytoplasmic organelles are removed.
• The ECM—composed mainly of collagen type II, proteoglycans, and glycosaminoglycans (GAGs)—is retained.
• Basophilic nuclear material, which typically binds hematoxylin, is absent.

As a result, the decellularized tissue lacks the bluish-purple coloration normally seen in native tissue sections stained with H&E. Instead, the tissue often appears light pink to pale depending on the density and composition of the remaining ECM.

Histological Observations Post-Transplantation: After transplantation, unless the scaffold has undergone host recellularization, the absence of nuclei continues to be evident in histological analysis. The ongoing lack of basophilic structures means that hematoxylin staining remains negative, and thus the bluish-purple hues are not observed.

Additionally, proteoglycan loss during decellularization may further alter the eosinophilic staining pattern, potentially reducing the intensity of the pink background stain, especially in cartilage.

Supporting Literature

Conclusion

The lack of bluish-purple coloration in H&E-stained sections of decellularized tracheal cartilage is a direct indicator of successful decellularization. It reflects the absence of nucleic acids—the primary target of hematoxylin—leaving only the ECM, which may stain lightly with eosin. Even after transplantation, unless significant cell repopulation has occurred, this staining pattern typically persists.