Extracellular matrix (ECM) proteins are non-cellular components of tissues, forming an intricate 3D protein network. In vitro, ECM proteins—commonly referred to as attachment factors—are added to culture dishes or other carriers to promote cell attachment. Key attachment factors include collagen, elastin, fibronectin, laminin, etc. By binding to cell surface receptors, they provide structural support and a microenvironment that enables intracellular communication, delivering essential mechanical and biochemical cues to maintain tissue homeostasis and regulate various cellular processes^[1].

Figure 1. Extracellular Matrix^[2].

Classification of Attachment Factors

Fibronectin is a high-molecular-weight protein found on cell surfaces and in plasma, typically existing as a disulfide-linked dimer. Its structure exhibits unique features: each monomer consists of 12 Type I, 2 Type II, and 15–17 Type III homologous modules, which together account for over 90% of its amino acid sequence ^[3-4]. Fibronectin interacts with various extracellular matrix (ECM) components and cell surface receptors. It plays critical roles in numerous physiological processes such as embryonic development, wound healing, hemostasis, and thrombosis. Dysregulated expression, defective degradation, or impaired assembly of fibronectin is closely linked to the pathogenesis of multiple diseases, including cancer and tissue fibrosis.

Figure 2. Structure of fibronectin^[4].

Laminin is predominantly localized in the lamina lucida of basement membranes, adjacent to the basal cell surface. It is composed of three polypeptide chains (α, β, and γ) linked by disulfide bonds, forming a distinctive cross-shaped structure. Functionally, laminin not only regulates fundamental cellular processes and functions but also promotes cell differentiation. In addition, it has been shown to significantly stimulate neurite outgrowth^[5-6].

Figure 3. Laminin forms diverse heterotrimeric complexes^[5].

Collagen serves as the primary structural component of animal connective tissues and is the most abundant functional protein in mammals. Structurally, collagen is made up of three polypeptide chains (α-chains) rich in glycine and proline residues, which are arranged in a triple helix conformation^[7]. Over 20 distinct types of collagens have been identified, including fibrillar collagens, fibril-associated collagens, and network-forming collagens^[8-9]. Due to its exceptional biocompatibility and versatile support for diverse cell types, collagen is widely utilized for in vitro cell culture systems.

Figure 4. Collagen protein structure^[10].

Gelatin is a high-molecular-weight protein derived from the partial hydrolysis of collagen, primarily composed of glycine, proline, and hydroxyproline^[11].It has significant applications in the biomedical field and is commonly used as a coating material for culture plates or dishes. Gelatin markedly improves the adhesion efficiency of hard-to-attach cells, such as embryonic stem cells and testicular cells, while also providing an optimal growth environment for complex cellular models, including neuroepithelial-like structures.

Vitronectin is a 478-amino-acid glycoprotein. Its mature form, with the signal peptide removed, contains 459 residues. It exists in circulation either as a 75 kDa single-chain protein or as a disulfide-linked double-chain variant comprising 65 kDa and 10 kDa subunits, primarily found in blood and the extracellular matrix. Vitronectin serves as an inhibitor of the cell-lytic complement pathway, and plays a vital regulatory role in coagulation. Moreover, vitronectin promotes the migration, proliferation, differentiation, and dissemination of endothelial and tumor cells^[12].

MCE offers a series of high-quality attachment factor products optimized to enhance the adhesion, differentiation, and proliferation of various cell types. These premium-grade products create an in vitro culture environment that closely mimics in vivo conditions, supporting normal cellular physiology and optimizing cell-cell interactions. Utilizing these products enables researchers to achieve more physiologically relevant outcomes in their cell culture studies.