Growth hormone stimulates the degradation of calcium phosphate biomaterial by human monocytes macrophagesin vitro

Abstract

This study investigated the effects of human growth hormone (hGH) on the monocyte/macrophage lineage, the first cell population involved in degradation of calcium phosphate ceramic after in vivo implantation. Monocytes isolated from human blood were cultured on biphasic calcium pellets (200 mg) for 8 days in the presence of lipopolysaccharides (LPS, 0.5 microgram/mL), hGH (10 and 50 ng/mL), or an association of LPS with hGH (10 and 50 ng/mL). Unlike LPS, hGH significantly decreased (about 25%) the total number of lacunae formed by monocytes. However, hGH induced the formation of lacunae with a greater surface area (about a 90% increase) as compared to the control. Finally, intense upmodulation (about a 250% increase) of lacuna surface area was observed in the presence of both soluble factors, suggesting that hGH and LPS act synergistically. In view of the development of a drug delivery system for hGH bone release, this study shows that hGH not only stimulates bone cells implicated in the synthesis of the extracellular matrix but also those involved in the early degradation of calcium phosphate biomaterial.

A Methodological Study for the Analysis of Apatite‐Coated Dental Implants Retrieved From Humans

“…38,40 Growth hormone (GH), a regulator of osteoblast regulation and osteoclastic resorption, similarly stimulates macrophages to induce synthetic calcium phosphate degradation. 41 Activated osteoclasts may also play an important role in implant coating integrity. During bone remodeling, the osteoclasts adhering to the bone surface pump out protons in the region, lowering the local milieu to acidic levels (pH 5) and resulting in hydroxyapatite dissolution.…”

Macroporous Biphasic Calcium Phosphate Scaffold with High Permeability/Porosity Ratio

“…4 Knowing that pure crystalline HA degrades slowly in vivo and that b-TCP degrades faster than expected, the concept of mixing those two has been studied extensively with particular attention paid to synchronizing the degradation rate with that of new bone formation. 5 The following aspects of BCP have been investigated: use as bone filler, 6 in vitro dissolution, 7 in vivo degradation, 8 as a carrier of bone marrow, 9 as a carrier of recombinant human bone morphogenetic protein 2 (rhBMP-2), 10 as a carrier of growth hormone, 11 and as a carrier of cells or scaffold for bone tissue engineering (TE). 12 Regeneration of skeletal tissues has been recognized as a new means for the reconstruction of skeletal defects.…”

Human Growth Hormone Locally Released in Bone Sites by Calcium-Phosphate Biomaterial Stimulates Ceramic Bone Substitution Without Systemic Effects: A Rabbit Study

“…The monocyte/macrophage lineage, one of the first cellular populations implicated in the degradation process of calcium‐phosphate ceramics after in vivo implantation, has been described as the target for GH, (27,37,50,51) which appears to be a factor capable of priming monocytes/macrophages (38,39) . These reports, together with our recent investigations demonstrating that hGH stimulates the degradation of calcium‐phosphate ceramic by activated human monocytes/macrophages, (40) could indicate the origin of hGH stimulatory effects on ceramic degradation during the early implantation period. However, the stimulatory effects of hGH on ceramic degradation were around 140% over control values and certainly involved other resorptive cell types able to degrade ceramic (e.g., osteoclasts) (52) .…”

“…Recent studies have also suggested that GH is implicated in the control of osteoclastic bone resorption activity through indirect support of osteoclast generation and activation probably mediated by IGF‐I (35,36) . Finally, GH may be involved in the stimulation of phagocytic cells, (37–39) and a previous study in our laboratory also demonstrated its stimulatory effects on the degradation of BCP by human monocytes (40) . These different indications of GH stimulatory effects on several cell lines implicated in bone synthesis and in the resorption/degradation process led us to study whether locally released human growth hormone (hGH) could stimulate the ceramic resorption/degradation process as well as bone ingrowth.…”