Short-Term Effects of Poly-L-Lactic Acid-b-Polyethylene Glycol Microsphere Injection on Different Adipose Tissue Types in Rats.

BACKGROUND

Wrinkles and sagging, characteristics of aging, are associated with reductions in collagen and fat. Poly-L-lactic acid (PLLA) is widely used clinically as a tissue filler owing to its good biocompatibility and ability to improve wrinkles and signs of aging. Despite extensive studies of the mechanism of action of PLLA when used as a dermal filler, few studies have examined its effects on adipose tissue.

OBJECTIVES

The short-term effects of PLLA-b-polyethylene glycol (PEG) microspheres implanted in subcutaneous back adipose tissue (BAT) and visceral epididymal adipose tissue (EAT) of rats were examined.

METHODS

The authors divided 15 male Sprague-Dawley rats into 5 groups based on implantation time, and PLLA-b-PEG microspheres were implanted into the BAT (3 groups were sampled at 6, 8, and 12 weeks) and EAT (2 groups were sampled at 6 and 12 weeks) of rats. Tissue samples were collected at different time points postimplantation and subjected to histological analyses using hematoxylin and eosin, Masson's trichrome, and immunofluorescence staining.

RESULTS

Implantation of PLLA-b-PEG microspheres into different adipose tissues resulted in a mild and persistent inflammatory reaction, increased fibrous connective tissue, and noticeable collagen regeneration. Immunofluorescence showed the upregulation of uncoupling protein (UCP) 1 and UCP2 in the visceral adipose tissue surrounding the implant.

CONCLUSIONS

PLLA-b-PEG microspheres exhibited good tissue compatibility and induced an increase in fibrous connective tissue postimplantation, potentially mitigating oxidative damage and improving adipose tissue quality.