Ultra-high-speed transmission technique based on multi-core fiber (MCF) has attracted great attention and is considered a promising candidate for next-generation backbone optical transport networks (OTNs). In this letter, we demonstrate the first real-time 448Tb/s metro-regional field trial over deployed uncoupled 7-core MCF cable using commercial 800Gb/s OTN transponders. The 800Gb/s transponders have a modulation rate up to 140-Gbaud, which enables the adoption of noise-tolerant probabilistic constellation shaping 16-ary quadrature amplitude modulation (PCS-16QAM) format to achieved the target bit rate. And advanced channel matching shaping (CMS) algorithms as well as forward error correction (FEC) encoding algorithms are further adopted to enhance the overall performance of the OTN transponders. Moreover, advanced multi-core fusion splicing approaches are utilized to reduce the span loss of MCF links. Thanks to the high-performance OTN transponders and advanced splicing technique, the field trial achieved a transmission distance of over 495 km.