Tissue engineering and regenerative medicine (TERM) may be defined as a translational discipline focused on the development of novel techniques, devices, and materials to replace or repair injured or diseased tissue and organs. The main approaches typically use cells, scaffolds, and signaling molecules, either alone or in combination, to promote repair and regeneration. Although cells are required to create new functional tissue, the source of cells, either from an exogenous allogeneic or autologous source or through the recruitment of endogenous (autologous) cells, is technically challenging and risks the host rejection of new tissue. Regardless of the cell source, these approaches also require appropriate instruction for proliferation, differentiation, and in vivo spatial organization to create new functional tissue. Such instruction is supplied through the microenvironment where cells reside, environments which largely consist of the extracellular matrix (ECM). The specific components of the ECM, and broadly the extracellular space, responsible for promoting tissue regeneration and repair, are not fully understood, however extracellular vesicles (EVs) found in body fluids and solid phases of ECM have emerged as key mediators of tissue regeneration and repair. Additionally, these EVs might serve as potential cell-free tools in TERM to promote tissue repair and regeneration with minimal risk for host rejection and adverse sequelae. The past two decades have shown a substantial interest in understanding the therapeutic role of EVs and their applications in the context of TERM. Therefore, the purpose of this review is to highlight the fundamental characteristics of EVs, the current pre-clinical and clinical applications of EVs in TERM, and the future of EV-based strategies in TERM.

Extracellular matrix (ECM) bioscaffolds have demonstrated therapeutic potential across a variety of clinical and preclinical applications for tissue repair and regeneration. In parallel, these scaffolds and their components have shown the capacity to modulate the immune response. Unlike synthetic implants, which are often associated with chronic inflammation or fibrotic encapsulation, ECM bioscaffolds interact dynamically with host cells, promoting constructive tissue remodeling. This effect is largely attributed to the preservation of structural and biochemical cues—such as degradation products and matrix-bound nanovesicles (MBV). These cues influence immune cell behavior and support the transition from inflammation to resolution and functional tissue regeneration. However, the immunomodulatory properties of ECM bioscaffolds are dependent on the source tissue and, critically, on the methods used for decellularization. Inadequate removal of cellular components or the presence of residual chemicals can shift the host response towards a pro-inflammatory, non-constructive phenotype, ultimately compromising therapeutic outcomes. This review synthesizes current basic concepts on the innate immune response to ECM bioscaffolds, with particular attention to the inflammatory, proliferative, and remodeling phases following implantation. We explore how specific ECM features shape these responses and distinguish between pro-remodeling and pro-inflammatory outcomes. Additionally, we examine the impact of manufacturing practices and quality control on the preservation of ECM bioactivity. These insights challenge the conventional classification of ECM bioscaffolds as medical devices and support their recognition as biologically active materials with distinct immunoregulatory potential. A deeper understanding of these properties is critical for optimizing clinical applications and guiding the development of updated regulatory frameworks in regenerative medicine.

Extracellular vesicle (EV) research and its application in regenerative medicine have expanded exponentially in the past few decades. However, the discovery of a specific type of EV covalently attached to the extracellular matrix (ECM) occurred less than ten years ago. These vesicles, termed matrix-bound nanovesicles (MBV), are a distinct subtype of EV present in soft tissues of mammalian ECM. Unlike other EV, MBV can only be isolated after tissue decellularization and enzymatic solubilization of the ECM, followed by standard EV isolation protocols. Due to their recent identification, the characterization of MBV composition, biogenesis and cellular interactions remains in its early stages. Despite this, initial studies are beginning to provide insight into these biological processes. Additionally, recent preclinical studies have reported that MBV elicit a potent immunomodulatory effect upon the myeloid compartment following local and systemic delivery. These findings suggest that MBV are an integral component of the ECM and play a critical role in disease progression and maintaining homeostasis. Recognition of the presence of MBV within ECM offers new opportunities for developing the next generation of ECM-based therapeutics and biomaterials. This chapter reviews current advancements in understanding MBV biogenesis and their interactions with cells. Additionally, preclinical studies utilizing MBV for therapeutic purposes are discussed, highlighting their potential applications and future directions.

Background: Matrix-bound nanovesicles (MBV) are extracellular vesicles (EVs) that are embedded within the extracellular matrix (ECM), and they have shown immunomodulatory effects in various cell types. The THP-1 cell line is often used to study monocyte and macrophage functions due to its easy culture potential and relatively simple conditioning into different macrophage phenotypes, but the optimal culturing conditions that allow MBV immunomodulation have not been established. Methods: In this study, we evaluated different culturing and differentiation conditions of THP-1 cells in which MBVs showed immunomodulatory effects. We also studied the effect of MBVs on relevant inflammation pathways (NF-κB and ERK 1/2). Results: Quantification of inflammatory cytokine IL-6 indicated modulation effects by MBVs in the majority of the conditions, but TNF-α showed very limited modulation. ERK1/p44 phosphorylation was significantly increased in MBV groups, but NF-κB protein p65 expression was unaffected. When compared to serum EVs, vesicle uptake by THP-1 cells remained low after 24 h. Multispectral flow cytometry analysis of THP-1 cells exposed to MBV and serum EVs showed internalization of lipids, proteins and RNA within the cells in higher cell proportions, but colocalization of the different vesicle components was not observed. Conclusions: Overall, this study provided insights into MBV immunomodulatory effects on THP-1 cells and compared the effects of MBV and serum EVs. Slight differences in modulation were observed between both EV sources, pointing to cargo differences that need further investigation.