Adipose tissue is a crucial energy-regulating organ in mammals, responsible not only for storing excess energy but also participating in body temperature maintenance and metabolic balance. Adipocyte development is a complex dynamic process, starting from mesenchymal stem cells with differentiation potential, which gradually proliferate and differentiate into preadipocytes, and ultimately form mature adipocytes capable of storing fat. Significant differences in fat deposition capacity exist among different pig breeds. For example, Tibetan pigs, a characteristic plateau breed in China, are renowned for their thick backfat and high intramuscular fat content, with an average fat percentage of 41% in adult individuals. In contrast, Duroc pigs, a globally widely farmed lean-type breed, have a lean meat percentage of 65% and a backfat thickness of only about 1.5 cm. Behind this difference, what is the regulatory mechanism of adipocyte development? Why can Tibetan pigs accumulate fat more efficiently?

A research team led by Professor Xiaoxiang Hu from the College of Biological Sciences, China Agricultural University, conducted an in-depth exploration of this issue using single-cell RNA sequencing technology. The relevant research has been published in Frontiers of Agricultural Science and Engineering (DOI: 10.15302/J-FASE-2025637).

The research team selected neck subcutaneous adipose tissue from 4-day-old Tibetan pigs and Duroc pigs, isolated stromal vascular fraction (SVF) cells containing various cell types, and analyzed cellular heterogeneity using single-cell RNA sequencing (scRNA-seq) technology. The results showed that both pig breeds contained multiple cell types in their adipose tissue, including mesenchymal stem cells, adipose stem cells, preadipocytes, and mature adipocytes, but the proportion of mature adipocytes in Tibetan pigs was significantly higher. Pseudotime analysis revealed that preadipocytes in Tibetan pigs were more inclined to differentiate into mature adipocytes rapidly, while most preadipocytes in Duroc pigs remained in an undifferentiated state.

Further gene function analysis indicated that the pathways related to fatty acid transport and thermogenesis were significantly enhanced in Tibetan pig adipocytes. For instance, at the stages of mesenchymal stem cells, adipose stem cells, and preadipocytes, the expression levels of fatty acid transport genes in Tibetan pigs were higher, implying their cells had a stronger ability to uptake fatty acids from the external environment. Meanwhile, the expression of the UCP3 gene, which is associated with non-shivering thermogenesis, was upregulated in Tibetan pig adipocytes, potentially helping Tibetan pigs maintain body temperature in the cold plateau environment. In contrast, adipocytes of Duroc pigs exhibited stronger oxidative metabolism capacity, with higher expression levels of mitochondria-related genes, indicating a faster energy consumption rate.

To verify the sequencing results, the research team cultured SVF cells of both pig breeds in vitro. Experiments showed that after 8 days of differentiation, the lipid droplet content in Tibetan pig cells was significantly higher than that in Duroc pig cells, and the expression level of fatty acid transport genes remained consistently high. In contrast, Duroc pig cells had stronger proliferation capacity, with significantly more cells than Tibetan pig cells after 24, 48, and 72 hours of culture. These results were consistent with the sequencing analysis, confirming the advantages of Tibetan pigs in adipocyte differentiation efficiency and fatty acid uptake capacity, as well as the characteristics of Duroc pigs in cell proliferation and energy metabolism.

This study revealed the cellular heterogeneity of porcine adipose tissue and its relationship with fat deposition through single-cell sequencing technology. It clarified that Tibetan pigs already possess stronger adipogenic potential in the early stages of adipocyte development, and the enhanced fatty acid transport activity of mature adipocytes is the key to their efficient fat deposition. Additionally, the lower metabolic activity and oxygen consumption of Tibetan pig adipocytes may be adaptive manifestations to the hypoxic plateau environment. These findings provide a new cellular and molecular mechanism for understanding the differences in fat deposition among pig breeds and offer guidance for improving fat content and stress resistance in pig breeding.

DOI：10.15302/J-FASE-2025637