The potential application of concentrated growth factor in pulp regenerationan in vitro and in vivo study

A tooth with no living tissue inside it — sealed, treated, done. That's how most people think about a root canal. But researchers are now regrowing the pulp inside teeth that conventional dentistry had written off, using a material spun out of the patient's own blood. Fangfang Xu and colleagues at Zhejiang University set out to find whether that material — concentrated growth factor, or CGF — could actually rebuild a living dental pulp, from cell biology all the way to a functioning tooth in a living animal. The problem they were trying to solve starts young. When a child or teenager gets a serious pulp infection in a tooth whose roots haven't finished forming, the infection doesn't just hurt — it freezes development. Root maturation stops. The walls of the root stay thin and brittle, and the tip of the root, the apex, stays wide open. The standard clinical fix is apexification: you plug the open apex and seal the canal. That stops the infection pathway. But the tooth is still structurally weak, still at higher risk of fracture, and still at higher risk of reinfection because the root never grew to full length and the walls never thickened. You've solved the immediate problem and accepted a permanent liability. Regenerative endodontic treatment — RET — is the alternative concept: don't just plug the canal, regrow what was lost. Replace the necrotic pulp with living, vascularized, innervated pulp-like tissue, and let the root keep developing. To do that, you need three things: stem cells, bioactive signaling molecules, and a scaffold to hold it all together. CGF supplies all three from a single source. Venous blood drawn from the patient is centrifuged in a stepped protocol — accelerating and decelerating between roughly 2,400 and 3,000 rotations per minute over about thirteen minutes total — which separates out a dense, cross-linked fibrin membrane packed with platelets and leukocytes. That membrane carries a payload of growth factors: platelet-derived growth factor BB, transforming growth factor beta-1, insulin-like growth factor 1, vascular endothelial growth factor or VEGF, and basic fibroblast growth factor, among others. These are the molecular signals that drive cell proliferation, recruitment, new blood vessel formation, and tissue differentiation. Because it comes from the patient's own blood, CGF is autologous — no donor risk, no immune rejection. The fibrin matrix itself acts as the scaffold. One material, one blood draw, three requirements met. To test whether CGF could actually work in an inflamed dental environment, Xu and colleagues first ran the experiment in a dish. They isolated human dental pulp stem cells — hDPSCs — from impacted third molars of donors aged fourteen to twenty, confirmed the cells had mesenchymal stem cell markers, and then deliberately inflamed them with lipopolysaccharide, or LPS, the toxic component of gram-negative bacterial cell walls. LPS is what pulp stem cells actually encounter during a real infection, and a concentration of one microgram per milliliter — the dose the team selected for most assays — falls squarely within the range reported in infected root canals. LPS on its own pushed the cells into an inflammatory state: expression of tumor necrosis factor alpha, interleukin-1 beta, interleukin-6, and interleukin-8 all climbed. This matters because sustained inflammation is exactly what stalls pulp repair in living tissue. Then, the researchers added CGF conditioned medium — prepared by freeze-drying CGF membranes, dissolving them in culture medium, and filtering — and watched what changed. Three things changed, and all three moved in the right direction. First, proliferation: the full-strength CGF preparation significantly boosted cell numbers by day three, and by days five and seven, the effect was dose-dependent across all but the most dilute concentration. Combined CGF plus LPS outperformed control from day three through day seven. Second, migration: in Transwell assays, CGF with or without LPS produced significantly denser migration than control. Strikingly, LPS alone generated more migrating cells than the serum-positive control — meaning bacterial signaling itself recruits stem cells, and CGF amplifies that recruitment further. Third, and most directly relevant to pulp repair, differentiation: alkaline phosphatase activity, an early marker of bone and tooth-forming cell commitment, was suppressed at day four when CGF and LPS were combined, but by day seven, CGF significantly promoted alkaline phosphatase activity in LPS-stimulated cells. By days twenty-one and twenty-eight, mineralized nodule formation was denser and larger in CGF-treated groups. Gene expression data confirmed the direction: DSPP, DMP-1, Runx2, and OCN — markers of odontoblastic and osteogenic commitment — were all significantly upregulated in CGF-treated cells at both time points. On the inflammatory side, CGF durably suppressed interleukin-8 expression from day one through day seven under LPS stimulation. Interleukin-8 is a chemokine that recruits inflammatory cells. Tamping it down without eliminating the recruitment signal entirely is exactly the kind of modulation you'd want in a tissue that needs stem cells to arrive but doesn't need uncontrolled inflammation to persist. That's the cell biology. The harder question is whether any of this survives contact with a real tooth. To find out, Xu and colleagues turned to three five-month-old beagle dogs and thirty-six immature single-rooted anterior teeth, randomly divided into three groups: CGF filling, positive control with no treatment, and negative control with pulp removed and canal prepared but nothing placed. Autologous CGF was prepared fresh from each animal's own blood, cut into two cubic millimeter fragments, and packed into the canals. Cavities were sealed with glass ionomer, and the dogs were monitored for eight weeks, then euthanized for radiographic and histological analysis. The radiographs told a preliminary story: CGF-filled teeth showed variable root wall thickening and closed apices at eight weeks, comparable to the untreated positive controls. Negative controls — empty canals — showed no wall thickening and no soft tissue ingrowth. But radiographs only show mineralized tissue. The histology revealed what was actually happening inside. In CGF-filled canals, hematoxylin-eosin and Masson trichrome staining showed connective tissue ingrowth with varying degrees of resemblance to normal dental pulp. Odontoblast-like cells arranged in a palisade pattern lined the interior of the root wall adjacent to newly forming pre-dentin. The central pulp space contained scattered blood vessels and collagen fibers stained blue by the Masson trichrome, indicating organized, vascularized connective tissue — not scar, not debris, but something architecturally close to what was lost. Negative controls showed empty lumina. Nothing. Immunohistochemistry added two more layers. VEGF staining was strong throughout the regenerated soft tissues in CGF-filled canals, particularly around blood vessels — matching the pattern seen in normal pulp and confirming active vascularization. Nestin, a marker of neural precursor cells found in functioning dental pulp, showed moderate overall staining with particularly intense signal in nerve-like cells within the regenerated tissue. Both markers were absent in negative controls. This is where the two halves of the study converge. In the dish, CGF recruited proliferating pulp stem cells, directed them toward odontoblastic identity, modulated inflammation, and promoted mineralization. In the canal, CGF-filled teeth showed exactly the tissue you'd predict from those cell behaviors: odontoblast-like cells depositing new dentin, blood vessels confirmed by VEGF, nerve precursors confirmed by Nestin, and continued root development. The biological logic runs straight from the in vitro result to the histological slide. The limitations are real and worth naming. This is a beagle model, not a human clinical trial. Eight weeks is a short window. Canine immature teeth differ from human clinical conditions in ways that matter for translating results. The inflammatory suppression by CGF is also selective and time-dependent — interleukin-8 durably reduced, interleukin-6 only transiently, tumor necrosis factor alpha with an early spike before later modulation — meaning the inflammatory microenvironment CGF creates is complex and not yet fully characterized. But the proof-of-concept is solid. An autologous material derived from a ten milliliter blood draw can, when placed in a surgically prepared immature root canal, support ingrowth of vascularized, innervated pulp-like tissue and continued root maturation over eight weeks. The next question is the obvious one: does it hold up in humans, over longer follow-up, in the variable conditions of clinical practice? That's what a trial would need to show. What this study establishes is that the biology is there, the scaffold works, and the leap from Petri dish to living tooth is shorter than it once seemed. This lecture was created by ennepō. Go to https://ennepo.ai to Discover, Create and Follow the latest research in your field. Read when you can. Listen when you want to.