Arye Shteyer

Histone H4-related osteogenic growth peptide (OGP): a novel circulating stimulator of osteoblastic activity.

It has been established that regenerating marrow induces an osteogenic response in distant skeletal sites and that this activity is mediated by factors released into the circulation by the healing tissue. In the present study we have characterized one of these factors, a 14 amino acid peptide named osteogenic growth peptide (OGP). Synthetic OGP, identical in structure to the native molecule, stimulates the proliferation and alkaline phosphatase activity of osteoblastic cells in vitro and increases bone mass in rats when injected in vivo. Immunoreactive OGP in high abundance is present physiologically in the serum, mainly in the form of an OGP‐OGP binding protein complex. A marked increase in serum bound and unbound OGP accompanies the osteogenic phase of post‐ablation marrow regeneration and associated systemic osteogenic response. Authentic OGP is identical to the C‐terminus of histone H4 and shares a five residue motif with a T‐cell receptor beta‐chain V‐region and the Bacillus subtilis outB locus. Since these latter proteins have not been implicated previously in the control of cell proliferation or differentiation, OGP may belong to a novel, heretofore unrecognized family of regulatory peptides. Perhaps more importantly, OGP appears to represent a new class of molecules involved in the systemic control of osteoblast proliferation and differentiation.

Cleidocranial dysplasia: Part 1–General principles of the orthodontic and surgical treatment modality

Over several decades, occasional reports of dental treatment provided by an individual practitioner to patients suffering with cleidocranial dysplasia have appeared in the literature. In the past, the main treatment was prosthetic replacement. Orthodontic treatment has only recently been considered as a serious treatment option, with success being described in several aspects of this treatment modality, in published individual case reports. Given the rarity of the condition, guidelines for the treatment of cleidocranial dysplasia are difficult to find in the literature, because few practitioners have treated enough cases to be in a position to make such recommendations. Two different approaches have been proposed in the past and are discussed here. The relative advantages of a third approach are expounded in detail.

Cleidocranial dysplasia: Part 2-Treatment protocol for the orthodontic and surgical modality

The principles on which the present approach to the treatment of cleidocranial dysplasia are based were stated in part 1 of this article. Comparison was made with two other methods and the advantages of the present method were described in terms of (a) how this method is adapted to the clinical features of the condition, (b) when surgical intervention is appropriate, (c) how the dynamic appliance system may be adapted to the changing environment as more teeth erupt, and (d) the importance of rapidly bringing about the eruption of the anterior teeth. The practical aspects of the treatment are now described step-by-step with illustrations taken from the treatment of several different patients.

Mitogenic action of osteogenic growth peptide (OGP) Role of amino and carboxy-terminal regions and charge

We have recently reported the discovery of a 14-amino-acid osteogenic growth peptide (OGP). In vivo OGP increases bone formation and trabecular bone density. Physiologically it is found in serum complexed to an OGP binding protein (OGPBP). In vitro OGP has a biphasic effect on osteoblastic MC 3T3 E1 and fibroblastic NIH 3T3 cell proliferation; at low concentrations (0.01-1.0 and 1.0-100.0 pM, respectively) it is highly stimulatory with an inhibition at higher doses. To assess possibilities of labeling synthetic OGP to obtain radio- or fluorescent ligands, OGP analogues were extended at the N- or C-termini with Cys or Cys(S-NEtSucc) or the OGP Tyr-10 replaced by 3-I(Tyr). All analogues with N-terminal modifications, as well as the [Cys15]OGP-NH2 retained the OGP-like dose-dependent effect on proliferation of the MC 3T3 E1 and NIH 3T3 cells, although the magnitude of stimulation was lower, approx. 2/3 that of the native-like synthetic OGP. The [Cys15(S-NEtSucc)]OGP-NH2 and [3-I(Tyr10)]OGP shared only the inhibitory activity of OGP. This suppression is further shared by a number of other positively and negatively net charged, but not net neutral, peptides. Both N-terminal-modified analogues displayed a decreased binding activity to the OGPBP. All analogues except reverse OGP, [3-I(Tyr10)]OGP and [Cys15(S-NEtSucc)]OGP-NH2 reacted with anti-OGP antibodies. These data are not only important for labeling purposes but suggest a respective role for the OGP N-and C-terminal regions in binding to the OGPBP and putative OGP receptor. It appears that the OGP proliferative activity represents the net effect of stimulation specific to the OGP structure and nonspecific inhibition associated with the peptides high positive net charge.

Isolation of osteogenic growth peptide from osteoblastic MC3T3 E1 cell cultures and demonstration of osteogenic growth peptide binding proteins

The osteogenic growth peptide (OGP) was recently characterized in regenerating bone marrow. In experimental animals it increases osteogenesis and hemopoiesis. In stromal cell cultures OGP stimulates proliferation, alkaline phosphatase activity, and matrix mineralization. OGP in high abundance is present in normal human and animal serum mainly complexed to OGP binding protein (OGPBP) or proteins. Here we show the presence of two OGPBPs, OGPBP‐1, and OGPBP‐2, in cultures of osteoblastic MC3T3 E1 cells. Immunoreactive OGP (irOGP) also accumulates in the medium of these cultures and in cultures of NIH 3T3 fibroblasts. A large amount of irOGP was released by heat inactivation of OGPBP‐2 and purified by ultrafiltration and hydrophobic HPLC. The purified irOGP was identical to OGP obtained previously from rat regenerating bone marrow and human serum in terms of its amino acid sequence, immunoreactivity, and mitogenicity. Osteoblastic and fibroblastic cell proliferation can be arrested by anti‐OGP antibodies and rescued by exogenous OGP, indicating that in the absence of serum or other exogenous growth stimulators the endogenously produced OGP is both necessary and sufficient for baseline proliferation. The OGP production is up‐ and down‐regulated, respectively, by low and high doses and exogenous OGP in a manner consistent with an autoregulated feedback mechanism. The most effective OGP dose in MC3T3 E1 cells is at least two orders of magnitude lower than that in non‐osteoblastic cell systems. This differential sensitivity of the osteoblastic cells could result in a preferential anabolic effect of OGP in bone. J. Cell. Biochem. 65:359–367.

Further Characterization of Osteogenic-Cell Growth Promoting Activity Derived from Healing Bone Marrow

During its osteogenic phase, post-ablation regenerating bone marrow produces bone promoting activity to osteogenic cells. In the experiments reported, activity derived from (rat) healing bone marrow conditioned medium (HBMCM) after boiling was analyzed using chromatography on heparin-Sepharose. The activity in HBMCM was shown to be divided among at least six independent activities that stimulated DNA synthesis rates is osteogenic rat osteosarcoma (ROS) cells. Three activities resolved when heparin-Sepharose was washed isocratically with phosphate buffered saline. Two of these were resistant to reduction and acidification and their effect was considerably more potent in osteogenic than non-osteogenic ROS cells. Three additional activity peaks recovered when the heparin-Sepharose column was pumped with an NaCl gradient. Two of them eluted at 0.3 and 0.65 M NaCl, affected osteogenic and non-osteogenic ROS cells to a similar extent and may be attributed to platelet-derived growth factor. A third peak, resolved at 1.2 M NaCl, implies the residual activity of acidic fibroblast growth factor that persisted after boiling of the conditioned medium. It is concluded that the activity profile of HBMCM reflects the in vivo situation where the osteogenic phase of marrow regeneration is probably regulated by multiple growth factor species.

Hormone-responsive cells derived from human dental papilla: Characterization in vitro and in vivo in diffusion chambers

SummaryCells of the dental papilla are capable of odontoblastic, fibroblastic, and endothelial differentiation and formation of dentin and the dental pulp. In the present study dental papilla cells, obtained from human tooth buds (HDP cells), were cultured in vitro through 3 to 7 passages. After exposure to prostaglandin E2 there was a marked decrease in intracellular cyclic AMP (cAMP) levels as compared to hormone-free controls. Parathyroid hormone and calcitonin had stimulatory effects with 1 and 2 log increases in cAMP, respectively. The HDP cells showed moderate activity of alkaline phosphatase, 1 log higher than that of hamster kidney fibroblasts (BHK 13) and 1 log lower than that of osteoblastic osteosarcoma cells (ROS 17/2). When cultured for 4 or 8 wk in diffusion chambers (DC) implanted in athymic mice, many of the HDP cells underwent odontoblastic morphodifferentiation with very long, single processes extending into the matrix. This matrix contained banded and unbanded collagen fibers. Neither light nor electron microscopy of the DC content revealed mineral deposits. These results suggest that HDP cells have an intrinsic potential for partial odontoblastic differentiation; inductive signals like those originating from odontogenic epithelium are probably essential for the completion of hard tissue formation.