What Is Microfat? Understanding Fat-Based Regenerative Injections for Joint Pain
If you have been researching regenerative options for joint pain or tissue repair, you have probably encountered terms like microfat, nanofat, micro-fragmented adipose tissue (mFAT), stromal vascular fraction (SVF), micronized fat grafting, stem cells, and fat transfer. These all start from the same source — adipose (fat) tissue — but they are processed very differently and used for very different purposes. The way fat is harvested, processed, and delivered directly determines what it can do once it reaches the target tissue.
At Solutions Regenerative Medicine in Tempe, Arizona, Dr. Mareshah Dunning uses micronized fat injection as part of a comprehensive regenerative approach to musculoskeletal care. This article explains where each preparation fits and why the choice of processing method matters.
What Is Adipose Tissue and Why Is It Used in Regenerative Medicine?
Adipose tissue, commonly known as body fat, is one of the most accessible and abundant sources of mesenchymal stem cells (MSCs), pericytes (cells that maintain blood vessel and tissue health), growth factors, and extracellular matrix (ECM) in the human body. But healing is far more complicated than simply adding stem cells to a joint. The therapeutic effect comes from the entire biological environment working together: MSCs signaling to surrounding cells, growth factors modulating inflammation, the ECM providing structural scaffolding, and pericytes supporting vascular health.
The ECM deserves particular attention. It is the structural framework that holds cells in place, delivers chemical signals, and creates the microenvironment cells need to function. When fat tissue is processed for injection, preserving or destroying this scaffold is the single biggest factor that separates one preparation from another.
What Is Microfat?
Microfat is adipose tissue harvested through liposuction (also called lipoaspiration) using small cannulas, typically 2 to 3 millimeters in diameter, then processed by centrifugation or decanting. The result is clusters of intact fat cells (adipocytes) measured in millimeters — primarily a structural, volumizing tissue designed for aesthetic and reconstructive fat transfer procedures like facial fat grafting, breast augmentation, and contour correction.
While microfat does contain MSCs and growth factors, its particle size is too large for precise injection into joints or tendons. To use fat therapeutically in musculoskeletal targets, it needs further processing to reduce particle size while preserving the biological components that drive repair.
How Is Fat Micronized and Why Does the Method Matter?
This is where the different preparations diverge. There are several ways to reduce fat particle size, and each method preserves or destroys different components of the tissue:
Mechanical emulsification (nanofat). Described by Tonnard and Verpaele in 2013, this technique passes harvested fat back and forth between syringes through small connectors, then filters it through a 400 to 600 micrometer mesh. This process destroys the intact adipocyte structure and the extracellular matrix. What remains is essentially a liquid containing free-floating SVF components: MSCs, growth factors, and cytokines, but without the scaffold that held them together. Published histologic analysis confirms that nanofat contains no viable adipocytes and no intact tissue architecture (Tonnard et al., 2013, PMID: 23783059).
Mechanical micronization with intact architecture (micronized fat / mFAT / micro-fragmented adipose tissue). This is what Dr. Dunning uses at Solutions Regenerative Medicine for musculoskeletal conditions. The body-jet® eco, a closed, water-assisted liposuction system, harvests fat using a gentle pulsating water jet rather than aggressive manual suction. The collected tissue is then processed through the FillerCollector® to create particles between 650 and 850 micrometers. No centrifugation or enzymatic digestion is required. The result is small enough for precise, image-guided injection but large enough to preserve the intact stromal vascular niche: the natural cellular neighborhood where MSCs, pericytes, and growth factors remain together in their native scaffold. The goal is not just to deliver cells to a damaged area, but to transplant a functioning biological environment where those cells can survive, signal, and support repair over time.
Cell isolation (isolated SVF or cultured MSCs). SVF can be isolated from adipose tissue through enzymatic methods (using collagenase) or mechanical methods (centrifugation, filtration, and washing without enzymes). Either way, the tissue architecture is broken down to release individual cells — a cell suspension with no intact structure. This approach is used in research settings and cell banking, where cells may be cultured, expanded, and cryopreserved. When the clinical goal is to increase cell count numbers, adding donor tissue or previously banked autologous cells can complement micronized fat.
What Does Nanofat Actually Provide Without the ECM?
Nanofat still contains SVF cells that can release growth factors, cytokines (VEGF, bFGF, IGF-1), and anti-inflammatory signaling molecules through paracrine activity. Published preclinical research has shown that nanofat can reduce cartilage degeneration and support chondrocyte function through these signaling pathways (Chen et al., 2021, PMID: 34446107).
For aesthetic applications like skin rejuvenation and scar improvement, nanofat is actually the preferred preparation — the smaller particle size makes it safer for highly vascularized facial tissue, where larger particles could pose embolic risk. But for musculoskeletal applications, free-floating cells in a demanding joint environment may not survive or signal long enough to produce meaningful repair. Dr. Dunning chooses micronized fat for joints because the preserved scaffold gives cells the support structure they need.
How Do These Preparations Compare?
| Microfat | Nanofat | Micronized Fat (body-jet® eco) | Isolated SVF / Banked Cells | |
| Particle size | Millimeter-scale | 400-600 µm | 650-850 µm | Individual cells |
| Tissue architecture | Intact adipocytes | Destroyed | Preserved stromal vascular niche | No tissue structure |
| ECM preserved | Yes (large clusters) | No | Yes (micronized particles) | No |
| Primary use | Volume / fat transfer (aesthetics) | Skin rejuvenation (aesthetics), safer for facial vasculature | Joint and soft tissue repair (MSK), scaffold preserved | Cell count augmentation, cell banking, future use |
| Autologous | Yes | Yes | Yes | Can be autologous or donor |
| Processing | Centrifugation / decanting | Mechanical emulsification + filtration | Water-assisted harvest + FillerCollector® | Enzymatic or mechanical isolation + culture |
| Suitable for joint injection | No, too large | Limited, no scaffold | Yes, designed for precise placement | Depends on preparation |
Frequently Asked Questions
Is microfat the same as micronized fat?
No. Microfat is harvested for volume restoration in aesthetic fat transfer procedures, with millimeter-scale particles designed for structural fill. Micronized fat (also called micro-fragmented adipose tissue or mFAT) is further processed into 650 to 850 micrometer particles that preserve the regenerative cells, growth factors, and extracellular matrix for joint and soft tissue injection. Dr. Dunning at Solutions Regenerative Medicine in Tempe, Arizona uses micronized fat for musculoskeletal conditions because it preserves the biological scaffold cells need to function.
What is the difference between autologous and donor tissue?
Autologous tissue comes from your own body — for micronized fat, fat is harvested from the abdomen, lower back, or flanks and processed during the same visit. Donor tissue (allogeneic) comes from an external source: perinatal tissue (umbilical cord, amniotic membrane) or adipose tissue processed into SVF. Dr. Dunning at Solutions Regenerative Medicine in Tempe, Arizona evaluates whether micronized fat alone, donor tissue, banked cells, or a combination is most appropriate for each patient.
Why use nanofat for aesthetics but micronized fat for joints?
Nanofat’s smaller particle size (400 to 600 micrometers) makes it safer for highly vascularized facial tissue, where larger particles could pose embolic risk. For musculoskeletal applications, micronized fat (650 to 850 micrometers) is preferred because the preserved extracellular matrix gives cells the structural support they need in a demanding joint environment.
Is the healing process just about adding stem cells to a joint?
No. The therapeutic benefit comes from the entire biological environment: MSCs signaling to surrounding cells, growth factors modulating inflammation, the extracellular matrix providing scaffolding, and pericytes supporting tissue health. This is why micronized fat, which preserves this full environment, is clinically different from isolated cell preparations.
Ready to find out if micronized fat injection is right for you?
Dr. Mareshah Dunning at Solutions Regenerative Medicine in Tempe, Arizona offers personalized consultations to evaluate your condition and determine the most effective regenerative approach for your goals. Book a consultation with Dr. Dunning or call (480) 995-9131.