Adipose tissue as a living drug: Stromal vascular fraction and adipose tissue-derived stem cells in regenerative medicine

Table 1 Comparison of traditional drugs, living drugs and extracellular vesicles

Characteristic	Conventional drugs	Living drugs	Acellular methods
Composition	Chemical compounds (e.g., small molecules, biologics)	Viable, metabolically active cells (e.g., stem cells, T cells)	Purified growth factors, EVs, cytokines
Mechanism of action	Act as inert agents to exert biochemical effects	Two mechanisms: (1) Secretion of trophic and immunomodulatory factors; and (2) Direct cell replacement or structural contribution	Mimic paracrine signaling but lack adaptive cellular activity
Cellular activity	Inert, no real-time interaction with cells	Senses surroundings, adapts to the microenvironment, integrates with physiological processes	Cannot sense environment, grow, or interact with other cells
Adaptive response	No adaptive response	Adaptive paracrine signaling and, in some cases, lineage contribution	No adaptability or real-time response
Examples	Small-molecule drugs, biologics (e.g., monoclonal antibodies)	Stem cells, T cells, NK cells, MSCs, CAR-T, TILs, iPSC-derived products	ASC-derived EVs, growth factors, cytokines
Therapeutic effects	Target specific biochemical pathways	Replicate, migrate to injury sites, secrete therapeutic factors, modulate immune response	Provide paracrine benefits but cannot replace or integrate into tissues
Sustained effect	Short-term effects, often require repeated administration	Potential for sustained therapeutic outcomes (e.g., CAR-T)	Limited sustained effect without live cell interactions
Integration with body	Does not integrate with body systems beyond biochemical effects	Integrates with body, modulates tissue repair, and immune response	No integration with body; only mimics certain therapeutic benefits
Regenerative potential	Limited regenerative capability	Can promote tissue repair, angiogenesis, and immunomodulation	Limited regenerative potential; mainly offers supportive factors
Safety concerns	Risk of side effects and toxicity	Risks related to cell survival, fate control, and immune rejection	Reduced safety concerns compared to whole cells but lacks dynamic response capabilities
Examples in therapy	Pain relief, antibiotics, cancer biologics	MSCs, CAR-T, TILs, NK cells in regenerative and oncological therapies	EVs from stem cells, purified cytokines in regenerative medicine

EVs: Extracellular vesicles; NK: Natural killer; MSCs: Mesenchymal stem cells; CAR-T: Chimeric antigen receptor T-cell; TILs: Tumor-infiltrating lymphocytes; iPSC: Induced pluripotent stem cell; ASC: Adipose-derived stem cell.