Imagine if damaged jawbone caused by trauma or disease could be restored using an artificial material implanted directly into the body. Before such a material can be used in humans, it must undergo a series of rigorous tests\u2014one of which involves observing how the body\u2019s cells respond to it under a microscope. This is what Dr. drg. Anne Handrini Dewi, M.Kes., and her team from the Department of Biomedical Dentistry, FKG UGM, conducted in a study published in the April 2023 edition of Indonesian Dentistry Magazine. The study tested bone scaffolds made from gypsum and calcium carbonate in Wistar rats at the Integrated Research and Testing Laboratory (LPPT) UGM, with the aim of comparing various histological staining methods for assessing tissue responses to the new implant material.<\/p>\n\n\n\n
Bone damage is a real challenge in dentistry and orthopedics. Various bone replacement materials, known as bone scaffolds or scaffolding materials, continue to be developed to support the regeneration of new bone. However, every new material must undergo biocompatibility testing: an evaluation to ensure that the material does not harm the body, does not trigger an excessive immune response, and genuinely supports tissue growth.<\/p>\n\n\n\n
In this study, the research team used twenty four-month-old male Wistar rats as experimental animals. Scaffolding materials made from gypsum, calcium carbonate, and gelatin were implanted at two different sites: beneath the skin (subcutaneously) and directly into the femur (thigh bone). Observations were conducted on days 3, 14, and 30 after implantation to examine how tissue responses developed over time.<\/p>\n\n\n\n
The procedures were performed under general anesthesia, with ethical oversight from the FKG UGM Ethics Committee. After the experimental animals were euthanized, the tissues surrounding the implants were cut into thin sections, processed, and then stained using various histological techniques for examination under a light microscope.<\/p>\n\n\n\n
The most interesting aspect of this study was the comparison of five histological staining methods, each providing different information about tissue conditions.<\/p>\n\n\n\n
Hematoxylin and Eosin (HE) is the most common and affordable method. With this staining, cell nuclei appear blue-purple, while the cytoplasm appears pink. On day 3 after subcutaneous implantation, neutrophils and macrophages were clearly visible, indicating a normal early inflammatory response. By day 14, new blood vessels and collagen fibers had begun to appear around the implant, indicating that tissue regeneration was beginning to take place.<\/p>\n\n\n\n
Mallory staining provides sharper contrast for collagen fibers, which appear dark blue. This method is useful for assessing collagen thickness and maturity\u2014indicators of how far the tissue regeneration process has progressed. Compared with HE, residual implant material was also more clearly visible with Mallory staining.<\/p>\n\n\n\n
TRAP (Tartrate-resistant acid phosphatase) is a specialized staining method for detecting osteoclasts, the cells responsible for \u201cbreaking down\u201d old bone during the remodeling process. With TRAP staining, osteoclasts appear dark red against a green bone background, making them much easier to identify than with conventional HE staining. These osteoclasts were found within specialized depressions on the bone surface known as Howship\u2019s lacunae.<\/p>\n\n\n\n
Toluidine Blue is particularly effective for detecting mast cells and indicating the maturity of newly formed bone. A deeper blue color indicates more mature bone. Using this method, osteoblasts\u2014the cells responsible for forming new bone\u2014could be seen arranged neatly along the surface of the existing bone.<\/p>\n\n\n\n
Immunohistochemistry with DAB (3,3\u2032-diaminobenzidine chromogen) is the most advanced technique among the five. This method uses specific antibodies to detect certain proteins in tissue, such as VEGF, a marker of angiogenesis or new blood vessel formation; IL-8 and IL-1\u03b2, markers of inflammation; and apoptotic proteins such as caspase-3. Detected proteins appear brown, and the intensity of the color reflects the severity of the tissue response.<\/p>\n\n\n\n