Scarlet Therapeutics closed a $4 million seed round to advance its manufactured red blood cell platform toward a first clinical application. The company said its manufactured RBCs behave similarly to natural RBCs in vivo, supporting a potential role as both a drug-delivery vehicle and a longer-term alternative to conventional transfusions. Scarlet plans its initial application around RBCs loaded with therapeutic proteins for rare metabolic diseases. The seed financing is positioned to help the company translate its manufacturing and functional claims into clinical feasibility and regulatory packages. The round reflects continued investor interest in cell-derived and cell-mimetic platforms that can reduce limitations of traditional biologics, especially where repeat dosing and logistics drive major cost and access constraints.