A bare punctuation/spacing command such as \newunit in a bibmacro throws off biblatex's punctuation tracker. Punctuation and spacing commands should always be wrapped in \setunit/\printunit if they appear in bibmacros or drivers; they can only appear without those wrappers in field formats.
Instead of
\renewbibmacro{in:}{\newline}
you need something like
\renewbibmacro{in:}{\printunit{\newunitpunct\newline}}
That way \newunitpunct\newline is added to the punctuation buffer and only printed when it is needed. You can read more about the punctuation tracker in What do \setunit and \newunit do? and section §4.11.7 Using the Punctuation Tracker (pp. 312-317 in v3.14) of the biblatex documentation.
Note that author = {{Adams RH, Alitalo K}}, is wrong. Several names must always be separated with an and and should be given in Family, Given or Given Family format regardless of the desired output (see How should I type author names in a bib file? and How to properly write multiple authors in bibtex file?). The output can be controlled by the style (see the MWE below: you need the terseinits option and a few other things).
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[backend=biber, style=numeric,
giveninits, terseinits]{biblatex}
\DeclareNameAlias{sortname}{family-given}
\DeclareNameAlias{author}{sortname}
\DeclareNameAlias{editor}{sortname}
\DeclareNameAlias{translator}{sortname}
\renewcommand*{\revsdnamepunct}{}
\DeclareDelimAlias{finalnamedelim}{multinamedelim}
\renewbibmacro{in:}{\printunit{\newunitpunct\newline}}
\renewcommand{\bibfootnotewrapper}[1]{\bibsentence#1}
\renewcommand*{\finentrypunct}{}
\begin{filecontents}[force]{\jobname.bib}
@article{adams,
author = {Adams, R. H. and Alitalo, K.},
title = {Molecular Regulation of Angiogenesis and Lymphangiogenesis},
journal = {Nat Rev Mol Cell Biol},
volume = {8},
number = {6},
year = {2007},
pages = {464--478},
}
\end{filecontents}
\addbibresource{\jobname.bib}
\addbibresource{biblatex-examples.bib}
\begin{document}
\cite{sigfridsson,adams}
\printbibliography
\end{document}
