An experimental setup to evaluate innovative therapy options for the enhancement of bone healing using BMP as a benchmark – a pilot study

Abstract

Critical or delayed bone healing in rat osteotomy (OT) models is mostly achieved through large defects or instability. We aimed to design a rat OT model for impaired bone healing based on age, gender and parity. The outcome should be controllable through variations of the haematoma in the OT including a bone morphogenetic protein (BMP) 2 guided positive control.Using external fi xation to stabilise femoral a 2 mm double OT in 12 month old, female Sprague Dawley rats after a minimum of 3 litters healing was characterised following in situ haematoma formation (ISH-group)), transplantation of a BMP charged autologous blood clot (BMP-group) and the artifi cial blood clot only (ABC-group) into the OT-gap. In vivo micro-computer tomography (μCT) scans were performed after 2, 4 and 6 weeks. After 6 weeks specimens underwent histological analyses.In μCT examinations and histological analyses no bony bridging was observed in all but one animal in the ISHgroup. In the BMP group complete bridging was achieved in all animals. The ABC-group showed less mineralised tissue formation and smaller bridging scores during the course of healing than the ISH-group.In this pilot study we introduce a model for impaired bone healing taking the major biological risk factors into account. We could show that the in situ fracture haematoma is essential for bone regeneration. Using BMP as a positive control the presented experimental setup can serve to evaluate innovative therapeutical concepts in long bone application.

CD133: Enhancement of Bone Healing by Local Transplantation of Peripheral Blood Cells in a Biologically Delayed Rat Osteotomy Model

“…The model accounted for major risk factors such as age, female sex, and the number of parities [21]–[28]. In 19 female ex breeder Sprague-Dawley rats (age 12 months, weight: 412 g ±22; minimum 3 litters) a mid-femoral double osteotomy was stabilized with an external fixator [21], [29]. The double osteotomy led to a 2 mm gap between the cortices.…”

“…In one group a bare artificial blood clot was implanted into the gap (ABC, n = 6), in the second group a CD133(+) cell-charged blood clot was implanted into the gap (CD 133(+), n = 6) and in a third group a CD34(+) cell-charged blood clot was added (CD34(+), n = 7). The data of 5 of the animals of the ABC-group has been used in a previous publication [21]. All animal experiments were carried out according to the policies and principles established by the AnimalWelfare Act.…”

“…The exact surgical procedure has been described before [21]. In brief: Under general intraperitoneally applied anaesthesia.…”

Human Maxillary Sinus Floor Elevation as a Model for Bone Regeneration Enabling the Application of One-Step Surgical Procedures

“…82 In an in vivo study in rats using a femoral osteotomy model, a 2-mm femoral gap stabilised by an external fixator device failed to heal within 6 weeks, whereas local application of rhBMP-2 within a blood clot showed proper bone healing with bony bridging. 117 This indicates that BMP-2 stimulates osteogenic differentiation of osteoprogenitor cells and might be beneficial for clinical application.…”

Histogram Feature–Based Classification Improves Differentiability of Early Bone Healing Stages From Micro-Computed Tomographic Data

“…A broad range of different healing stages after 6 weeks of consolidation was achieved by different treatments, that is, implantation of progenitor cells, body morphogenetic protein 2 or blood clots into the OT gap. 14 The animal experiments were carried out following the protocol described elsewhere. 15 Micro-CT scans were conducted after 6 weeks of consolidation.…”