Clinical Efficacy of Adipose-Derived Stem Cell-Enriched Lipotransfer Versus Conventional Fat Grafting: A Systematic Review and Meta-Analysis.

Autologous fat grafting is a standard procedure for soft tissue reconstruction, yet its clinical utility is often compromised by unpredictable resorption rates. Cell-assisted lipotransfer (CAL), which enriches fat grafts with adipose-derived stem cells (ASCs) or stromal vascular fraction (SVF), has been proposed to stabilise retention through improved neovascularisation and paracrine support. This systematic review evaluates the clinical efficacy, safety, and oncological outcomes of CAL compared to conventional lipofilling. A systematic literature search was conducted across PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Science, Excerpta Medica database (EMBASE), and Cochrane Library databases following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Inclusion criteria were randomised controlled trials (RCTs) and cohort studies comparing enriched versus non-enriched fat grafts in humans. The primary outcome was volumetric retention, while secondary outcomes included complications and oncological safety. A random-effects meta-analysis was performed using Stata 15.1 (StataCorp LLC, College Station, TX) and Simple Meta-Analysis software (Learn Meta-Analysis LLC) to calculate standardised mean differences (SMD), and heterogeneity was assessed using Cochran's Q and the I² statistic. Fifteen studies meeting the inclusion criteria were analysed. The meta-analysis indicated a statistically significant improvement in graft survival favouring the enriched groups (SMD 2.44; 95% CI 1.00 - 3.88; p = 0.001). However, extreme statistical heterogeneity was observed (I² = 97.19%), suggesting that the magnitude of benefit is highly variable. Subgroup analysis revealed that enrichment effects were most pronounced in facial applications (SMD 2.95) and studies utilising standard aspiration techniques (SMD 2.94). Conversely, studies employing water-assisted lipotransfer (WAL) showed no significant added benefit to enrichment (SMD -0.22), supporting a harvest-quality ceiling hypothesis where a high-quality baseline harvest may render enrichment redundant. A secondary meta-analysis of patient satisfaction scores revealed no significant difference between the groups (p = 0.52). However, the enriched cohort demonstrated significantly higher costs and longer operative times. Long-term follow-up in post-mastectomy breast reconstruction patients did not demonstrate an increased risk of locoregional recurrence of malignancy. Current evidence suggests that CAL has the potential to improve volumetric retention compared to conventional fat grafting, particularly in facial reconstruction and when standard aspiration methods are used. However, the efficacy is context-dependent, and the high heterogeneity suggests that CAL cannot be considered uniformly superior across all harvesting techniques and recipient sites. Furthermore, although available evidence does not show an increased oncological risk during the reported follow-up periods, longer-term surveillance remains necessary to confirm these safety profiles. To establish reliable clinical guidelines, future trials must prioritise larger patient cohorts and standardised cell-dosing protocols to minimise procedural variability.