Increase in periosteal angiogenesis through heat shock conditioning

Abstract

ObjectiveIt is widely known that stress conditioning can protect microcirculation and induce the release of vasoactive factors for a period of several hours. Little, however, is known about the long-term effects of stress conditioning on microcirculation, especially on the microcirculation of the periosteum of the calvaria. For this reason, we used intravital fluorescence microscopy to investigate the effects of heat shock priming on the microcirculation of the periosteum over a period of several days.MethodsFifty-two Lewis rats were randomized into eight groups. Six groups underwent heat shock priming of the periosteum of the calvaria at 42.5°C, two of them (n = 8) for 15 minutes, two (n = 8) for 25 minutes and two (n = 8) for 35 minutes. After 24 hours, a periosteal chamber was implanted into the heads of the animals of one of each of the two groups mentioned above. Microcirculation and inflammatory responses were studied repeatedly over a period of 14 days using intravital fluorescence microscopy. The expression of heat shock protein (HSP) 70 was examined by immunohistochemistry in three further groups 24 hours after a 15-minute (n = 5), a 25-minute (n = 5) or a 35-minute (n = 5) heat shock treatment. Two groups that did not undergo priming were used as controls. One control group (n = 8) was investigated by intravital microscopy and the other (n = 5) by immunohistochemistry.ResultsDuring the entire observation period of 14 days, the periosteal chambers revealed physiological microcirculation of the periosteum of the calvaria without perfusion failures. A significant (p < 0.05) and continuous increase in functional capillary density was noted from day 5 to day 14 after 25-minute heat shock priming. Whereas a 15-minute exposure did not lead to an increase in functional capillary density, 35-minute priming caused a significant but reversible perfusion failure in capillaries. Non-perfused capillaries in the 35-minute treatment group were reperfused by day 10. Immunohistochemistry demonstrated an increase in cytoprotective HSP70 expression in the periosteum after a 15-minute and a 35-minute heat shock pretreatment when compared with the control group. The level of HSP70 expression that was measured in the periosteum after 25 minutes of treatment was significantly higher than the levels observed after 15 or 35 minutes of heat shock exposure.ConclusionA few days after heat shock priming over an appropriate period of time, a continuous increase in functional capillary density is seen in the periosteum of the calvaria. This increase in perfusion appears to be the result of the induction of angiogenesis.

Alendronate reduces periosteal microperfusion in vivo

“…The construction and implantation of the chamber have been previously described in detail [ 13 , 18 ].…”

“…The frame of the chamber was placed on the periosteum and sutured to adjacent skin in such a way as to prevent drying (Ethicon Vicryl sutures 5–0, Johnson & Johnson, Germany). Finally, the cover glass was secured to the frame with a circlip [ 13 ].…”

“…The periosteum is a highly vascularised tissue covering the bone and critically affects bone regeneration after any kind of trauma or infection by contributing to the blood supply to the cortical bone. Periosteal activity is believed to be of crucial importance in bone physiology and pathophysiology, and therefore, in the healing process [ 13 ]. A basic requirement for the preservation of periosteal function is the presence of adequate blood flow in periosteal vessels, because normal healing seems to be critically linked to the reestablishment of periosteal microcirculation [ 14 , 15 ].…”

“…However, limited data are available regarding alterations in capillary blood supply following bisphosphonate treatment. This blood supply can be measured by the functional capillary density which is defined as the total length of blood-cell-perfused microvessels in an observation area [ 13 ]. Interestingly, functional capillary density of the iris has been shown to be decreased by systemic inflammations [ 17 ].…”

Subperiosteal preparation using a new piezoelectric device: a histological examination

“…Such procedures damage important regenerative cells of the periosteum, which are thus no longer available to provide nourishment to the bone they cover. In order to reduce these microtraumata different approaches have been tried [ 6 ].…”