Male nude mice

Subconfluent human BM-MSCs and PDGFRα⁺ and CD56⁺ cells (2–3 amplification passages) were collected for subcutaneous implantation into the flanks of 10-week-old male nude mice (Janvier Labs). Implants were prepared by mixing 2 × 10⁶ cells with sterile 80–200 µm particles (60% hydroxyapatite/40% ß-tricalcium phosphate) (Graftys) and 100 μL of human plasma in a 1 mL syringe as described.^{59 (link)} Control “plasma implants” did not contain cells. Ten microliters of 2% CaCl₂ in water was added to induce coagulation. Fifteen weeks after implantation, animals were euthanized, scaffolds were collected and fixed in 4% paraformaldehyde overnight at 4 °C. The following day, scaffolds were washed with PBS and decalcified in 20% EDTA pH = 8 solution for 48 h. Implants were washed with PBS and dehydrated with a graded series of ethanol solutions prior to paraffin embedding (Thermo Scientific).

Male NUDE mice (Janvier SA, Le Genest St Isle, France) 6/8 weeks old were received and housed in a temperature-controlled room (21 ± 1 °C). They were allowed free access to water and fed standard pellets. The mice were anesthetized by a 2:1 (v/v) ketamine and xylazine mixture diluted in 0.9% NaCl and injected at 0.1 ml/g, and a single WBI dose was delivered by a medical accelerator (Alphée). Alphée is an accelerator-type radiation source (maximum energy 4 MeV with an average energy of about 1.5 MeV; 30 kA). The doses used were 15, 13, 12, and 10 Gy.