Fabricating 3-dimensional human brown adipose microtissues for transplantation studies

Area of Science:

• Regenerative Medicine
• Metabolic Disorders
• Biotechnology

Background:

• Cell-cultured brown adipocytes (BAs) show promise for treating obesity (OB) and type 2 diabetes mellitus (T2DM).
• Transplanted BAs suffer low survival rates in vivo, and enzymatic dissociation further reduces cell yield.
• Novel methods are needed to enhance BA survival during preparation, transplantation, and in vivo.

Purpose of the Study:

• To develop and evaluate injectable brown adipocyte microtissues as a strategy to improve cell survival and therapeutic efficacy.
• To assess the scalability, cryopreservation, and in vivo performance of engineered BA microtissues.
• To investigate the therapeutic potential of BA microtissues in mouse models of obesity and type 2 diabetes.

Main Methods:

• Brown adipocytes were cultured in 3D to promote differentiation and UCP-1 expression, optimizing aggregate size to 100 μm.
• Injectable microtissues were fabricated using 3D suspension culture with PEG hydrogel, enabling large-scale production and cryopreservation.
• The efficacy of transplanted microtissues was evaluated in high-fat diet-induced obese and T2DM mice.

Main Results:

• Engineered 3D BA microtissues demonstrated enhanced differentiation and UCP-1 expression.
• Fabricated microtissues exhibited long-term survival in vivo and significantly alleviated body weight and fat gain.
• Transplanted microtissues improved glucose tolerance and insulin sensitivity in obese and T2DM mice, impacting multiple organs and adipokine secretion.

Conclusions:

• Preparing brown adipocytes as injectable microtissues overcomes cell death issues during preparation and transplantation.
• Engineered 3D human BA microtissues offer advantages in scalability, storage, purity, safety, dosage, survival, and efficacy.
• This study presents the first report of fabricating human BA microtissues and demonstrating their safety and efficacy in T2DM mice.