Adipose tissue

In biology, adipose tissue Listeni/ˈædɨˌpoʊs/ or body fat or just fat is loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular endothelial cells and a variety of immune cells (i.e., adipose tissue macrophages [ATMs]). Adipose tissue is derived from preadipocytes. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body. Far from hormonally inert, adipose tissue has, in recent years, been recognized as a major endocrine organ, as it produces hormones such as leptin, estrogen, resistin, and the cytokine TNFα. Moreover, adipose tissue can affect other organ systems of the body and may lead to disease. The two types of adipose tissue are white adipose tissue (WAT), which stores energy, and brown adipose tissue (BAT), which generates body heat. The formation of adipose tissue appears to be controlled in part by the adipose gene. Adipose tissue – more specifically brown adipose tissue – was first identified by the Swiss naturalist Conrad Gessner in 1551.

Fat is an ideal sealant because it is impermeable to water.

see fat graft

Allogeneic adipose tissue-derived mesenchymal stem cells (ADMSCs) refer to a type of stem cell that is derived from adipose tissue (fat) and can be used for therapeutic purposes. These stem cells have the ability to differentiate into various cell types and possess immunomodulatory properties.

In a preclinical experimental study (Wistar rat model of volumetric muscle loss) Cantarero et al. from:

1. Research Group in Muscle Regeneration, Department of Morphological and Socio‑Sanitary Sciences, Faculty of Medicine and Nursing, University of Cordoba, Cordoba, Spain
2. Maimonides Institute for Biomedical Research of Cordoba (IMIBIC), Reina Sofía University Hospital, University of Cordoba, Cordoba, Spain
3. Dementia and Multiple Sclerosis Unit, Neurology Service, Reina Sofía University Hospital, Cordoba, Spain
4. Department of Neurosurgery and Clinical Neurophysiology, Reina Sofía University Hospital, Cordoba, Spain
5. Department of Pathology, Torrecardenas University Hospital, Almería, Spain
6. Sectoral Tissue Bank, Tissue Establishment of the Center for Transfusion, Tissues and Cells, Córdoba, Spain

published in the Journal *Anatomical Record (Hoboken)* 25 June 2025 with the purpose to assess and compare the efficacy of fresh versus cryopreserved autologous adipose tissue grafts in promoting regeneration, vascularization, innervation, and reducing fibrosis in volumetric muscle loss (VML) in rats. Both fresh and cryopreserved autologous adipose grafts significantly enhanced muscle fiber regeneration, reduced fibrosis (with increased type III collagen), boosted microvascular density, and improved signs of reinnervation. Cryopreservation did not compromise outcomes, supporting its use in tissue banking for regenerative medicine ¹⁾.

* Methodological flaws:

1. Only male Wistar rats? Sex not defined; potential gender bias.
2. 60-day endpoint insufficient to assess long-term muscle functionality – no biomechanical strength testing.
3. Quantitative histology may obscure patchiness of regeneration; need whole‑muscle mapping or imaging.
4. Lack of functional assays (force, fatigue resistance, gait), undermining clinical relevance.
5. Cryopreservation protocol inadequately detailed (freeze‑thaw rate, cryoprotectants, viability assays missing).
6. No controls for adipose‑derived cell viability or secretome analysis post‑thaw.
7. Statistical power unclear – no sample size calculation reported.

* Relevance & novelty:

1. The idea of adipose grafts for VML is not novel; prior studies exist.
2. Comparing fresh and cryopreserved is incremental, not groundbreaking.
3. Translational leap questionable without functional data or large animal/clinical steps.

* Interpretation issues:

1. Claim of “reintegration” based solely on histology; lacks electrophysiological or contractility validation.
2. Higher type III collagen may signal ongoing immature fibrosis, not necessarily better remodeling.
3. Vague immunohistochemical markers: vessel density and innervation should be quantified with objective metrics (e.g., CD31, neurofilament intensity)—not reported here.

* Conclusions oversold:

1. Authors suggest cryopreservation “did not diminish outcomes,” yet no viability assays or functional measures support equivalence.
2. Findings in rats may not extrapolate; graft volume, site, and immunogenic context differ in humans.

This is an underpowered descriptive histological study with questionable novelty and no functional verification. It raises more questions than provides solutions.

Histological signs of vascular and nerve regeneration after adipose grafting are encouraging, but without biomechanical and electrophysiological data, the work remains preclinical speculation—not ready to influence reconstructive paradigms.

Preliminary evidence supports the histological plausibility of cryopreserved adipose tissue aiding muscle regeneration, but the study lacks rigor and functional validation. Not ready for translation.