Oxysterols as promising small molecules for bone tissue engineering: Systematic review

Table 2 Descriptive summaries of the identified studies investigating the effect of oxysterols on bone formation in critical-sized alveolar defect models (n = 2)

Ref. (level of evidence)	Species (n)	Surgical model and scaffold(s) used	Experimental groups (n)		Assessment method and time point	Bone regeneration (%):1
Lee et al[35], 2017 (V)	Rat (n = 9)	Regeneration of critical-size alveolar defects (left and right maxillary first molars) using equimolar amounts of 20(S)-OHC and 22(S)-OHC (dissolved in 1% DMSO in PBS) or rhBMP-2 in solution	A. DMSO only (control) (n = 3)		Bone regeneration as assessed via µ-CT at 15 days of healing.	A. Approximately 45%
			B. 15-µg rhBMP-2 (n = 3)			B. Approximately 53%
			C. 0.40-µg of 20(S)-OHC and 22(S)-OHC (n = 3)			C. Approximately 65%
Bakshi et al[37], 2019 (V)	Rat (n = not reported)	Regeneration of a critical-size alveolar defect (7 mm × 4 mm × 3 mm) using a collagen sponge supplemented with rhBMP-2 or a mixture of 20(S)-OHC and 22(R)-OHC oxysterols	A. No treatment		Bone regeneration as assessed via µ-CT at 8 weeks of healing.	A. Approximately 65%
			Collagen sponge	B. No additive		B. Approximately 72%
				C. 12.5-µg of rhBMP-2		C. Approximately 92%a
				D. 20-mg of 20(S)-OHC and 22(R)-OHC		D. Approximately 90%a

¹Percent bone regeneration of critical-sized defect.

^aP < 0.05, compared to collagen sponge only and to no treatment. rhBMP-2: Recombinant human bone morphogenetic protein-2; OHC: Hydroxycholesterol; DMSO: Dimethyl sulfoxide; PBS: Phosphate buffer solution; µ-CT: Micro-computed tomography.